Vacuum  Cleaning  Systems 

A  Treatise  on  the  Principles  and 
Practice  of  Mechanical  Cleaning 


BY 


M.  S.  COOLEY,  M.  E. 

\\ 

MECHANICAL  ENGINEER  IN  OFFICE  OF  THE  SUPERVISING 
ARCHITECT,  TREASURY  DEPARTMENT,  WASHINGTON,  D.  C. 


FIRST  EDITION 


New  York: 

HEATING  AND  VENTILATING   MAGAZINE  COMPANY, 
1123   Broadway 


\ 
I* 


Copyright,    1913, 

BY 

HEATING  AND  VENTILATING  MAGAZINE  Co. 


CONTENTS. 

CHAPTER  I. 

HISTORY  OF  MECHANICAL  CLEANING. 

PAGE 

Early  Attempts   3 

Limitations  of  the  Carpet  Sweeper   4 

Compressed  Air  Cleaners    5 

Vacuum  Produced  by  Compressed  Air 7 

Compressed  Air  Supplemented  by  Vacuum  7 

Piston  Pump  the  First  Satisfactory  Vacuum  Producer.  .  .  9 

Systems  Using  Vacuum  Only 11 

Renovator  with  Inrush  Slot   13 

Steam  Aspirators  Used  as  Vacuum  Producers   14 

Piston  Pump  Used  Without  Separators 15 

First  Portable  Vacuum  Cleaner 15 

First  Use  of  Stationary  Multi-Stage  Turbine  Blowers 16 

Separators  Emptying  to  Sewer  by  Air  Pressure 18 

Machines  Using  Root  Blowers  as  Vacuum  Producers 18 

CHAPTER  II. 

REQUIREMENTS  OF  AN  IDEAL  VACUUM  CLEANING  SYSTEM. 

Necessity  and  Proper  Location  of  Stationary  Parts 24 

CHAPTER  III. 
THE  CARPET  RENOVATOR. 

Four  Important  Parts  of  Vacuum  Cleaning  System- 25 

The  Straight  Vacuum  Tool 26 

Renovator  with  Auxiliary  Slot  Open  to  Atmosphere 27 

Renovator  with  Two  Cleaning  Slots  30 

Renovator  with  Inrush  Slots  on  Each  Side 30 

Tests  on  Dirty  Carpets   30 

iii 


iv  CONTENTS 

PAGE 

Type  A  Renovator  Most  Efficient  on  Dirty  Carpets 36 

Tests  of  Carpets  " Artificially"  Soiled 36 

Effort  Necessary  to  Operate  Various  Type  of  Renovators.  .  51 
Relative  Damage  to  Carpets  with  Various  Type  of  Reno- 
vators   52 

CHAPTER  IV. 
OTHER  RENOVATORS. 

Different  Form  of  Renovator  Necessary  to   Clean  Walls, 

Ceilings  and  Similar  Flat  Surfaces 60 

Upholstery  Renovators  Disastrous  to  Surfaces  Cleaned ...  64 
Attempts  to  Overcome  Destructive  Tendency  of  Straight- 
Slot  Upholstery  Renovator   64 

Upholstery  Renovators  Most  Serviceable  Clothing  Cleaners.  65 

Special  Renovators  for  Cleaning  Stairs   .  . . 66 

Renovation  of  Furs   66 

Renovation  of  Pillows    66 

CHAPTER  V. 
STEMS  AND  HANDLES. 

Use  of  Drawn  Steel  Tubing  for  Stems  of  Cleaning  Tools.  .  70 

Drawn  Aluminum  Tubing  for  Long  Stems 71 

Swivel  Joints  Between  Renovator  and  Stem 72 

Wear  on  Hose  Near  Stem 74 

Methods  of  Overcoming  Wear  of  Hose  74 

Valves  to  Cut  Off  Suction 78 

CHAPTER  VI. 
HOSE. 

Early  Types  Made  of  Canvas- Wound  Rubber  Tubing 80 

Standard  Weight  Adopted   80 

First  Type  Produced  Especially  for  Use  in  Vacuum  Clean- 
ing Work 81 

First  Attempt  to  Produce  Light- Weight  Hose 81 

Other  Types   82 


CONTENTS  v 

PAGE 

Hose  Couplings    82 

Hose  Friction  84 

Effect  of  Hose  Friction  88 

Most  Economical  Hose  Size  for  Carpet  and  Floor  Renovators     93 

Conditions  for  Plant  of  Small  Power 97 

Limit  of  Length  for  Hose 99 

CHAPTER  VII. 
PIPE  AND  FITTINGS. 

Hose  Inlets . .  100 

Pipe  Friction   , 107 

Determination  of  Proper  Size  Pipe 107 

Determination  of  Number  of  Sweepers  to  be  Operated.  . . .  113 

Determination  of  Number  of  Risers  to  be  Installed 115 

Size  of  Risers  115 

Illustration  of  Effect  of  Long  Lines  of  Piping 120 

CHAPTER  VIII. 

SEPARATORS. 

Classification  of  Separators 127 

Primary  Separators    „ 127 

Secondary  Separators 130 

Complete    Separators    134 

Total  Wet  Separator   138 

CHAPTER  IX. 
VACUUM  PRODUCERS. 

Types  of  Vacuum  Producers   142 

Displacement    Type    142 

Centrifugal  Type 142 

Power  Required  to  Produce  Vacuum 142 

Reciprocating  Pumps   143 

Rotary  Pumps   148 

Centrifugal  Exhausters    156 

Steam  Aspirators 162 


vi  CONTENTS 

CHAPTER  X. 
CONTROL. 

PAGE 

First  Type  of  Controller    166 

Second  Form  of  Control  168 

Appliances  for  Varying  Speed  of  Motor-Driven  Vacuum 

Pump    171 

CHAPTER  XI. 
SCRUBBING  SYSTEMS. 

First  Real  Mechanical  Scrubbing  Device 176 

Combining  Scrubbing  with  Dry  Cleaning 177 

Ideal  Separator  for  Use  with  a  Combined   Cleaning  and 

Scrubbing  System   173 

CHAPTER  XII. 
SELECTION  OP  CLEANING  PLANT. 

Renovators    179 

Hose 182 

Pipe  Lines 182 

Separators 182 

Vacuum  Producers    183 

Control 183 

Selection  of  Appliances  for  Four  Classes  of  Work 184 

CLASS  1. — Plant  for  Residence  or  Small  Office  or  De- 
partmental Building,  to  be  Not  More  than 
One- Sweeper  Capacity. 

CLASS  2. — Large    Office     or     Departmental     Building 
Where   Carpet   Cleaning   is   Important   and 
Pipe  Lines  are  of  Reasonable  Length. 
CLASS  3. — Large    Building    or    Group    of    Buildings 
Where   Carpet    Cleaning   is   Important   and 
Long  Lines  of  Piping  are  Necessary. 
CLASS  4. — Large  or  Small  Plant  Where  Carpet  Clean- 
ing is  Not  an  Important  Function  of   the 
Cleaning  System 


CONTENTS  vii 

CHAPTER  XIII. 
TESTS. 

Early  Methods  of  Testing  187 

Most  Rational  System  of  Testing 189 

Use  of  Vacometer   190 

Proper  Orifice  to  be  Used  with  Each  Class  of  Plant 191 

CHAPTER  XIV. 
SPECIFICATIONS. 

Award  of  Contracts  on  Evaluation  Basis  193 

Determination  Basis  of  Evaluation  193 

Specification  for  Class  1,  Plant  for  Residence  or  Small 

Office  Building  of  One-Sweeper  Capacity 194 

Specification  for  Class  2,  Plant  for  Large  Office  Building 

Having  Pipe  Lines  of  Moderate  Length 204 

Specification  for  Class  3,  Large  Installation,  with  Unusually 

Long  Pipe  Lines  209 

Specification  for  Class  4,  Large  or  Small  Plant  Where 

Carpet  Cleaning  is  of  Secondary  Importance 215 

Specification  for  Class  5,  To  Give  Widest  Competition ....  218 

CHAPTER  XV. 
PORTABLE  VACUUM  CLEANERS. 

Power  Required  228 

Weight  of  Efficient  Portable  Cleaners 228 

Limit  of  Power  Consumption  When  Attached  to  Lighting 

System   • 229 

Disadvantage  of  Having  Dust  Bag  at  Outlet  of  Fan 230 

Portables  Equipped  with  Mechanically-Operated  Brushes. .  231 

Portables  Exhausting  Air  Inside  of  Building 231 


TABLES. 

PAGE 

1.  Cleaning  Tests  of  Dirty  Carpets  34 

2.  Cleaning  Tests  of  Carpets  Filled  with  Quicksand 38 

3.  Cleaning  Tests  Using  1  oz.  of  Sand  per  Square  Yard 

of  Carpet  40 

4.  Comparison  of  Tests  Made  by  Mr.  Reeve  and  by  the 

Author    48 

5.  Effort  Necessary  to  Operate  Cleaning  Tools 51 

6.  Vacuum  Required  at  Hose  Cock  to  Operate  Type  A 

Renovators  Attached  to  Varying  Lengths  of  Different- 
Sized  Hose 89 

7.  Air  Quantities  and  Vacuum  at  Renovator  with   1-in. 

Hose  and  10  in.  Vacuum  at  Hose  Cock 90 

8.  Air  Quantities  and  Vacuum  at  Renovator  with  1^4-in. 

Hose  and  6  in.  Vacuum  at  Hose  Cock 90 

9.  Vacuum  Required  at  Hose   Cock  to  Operate  Type   C 

Renovators  with  Various  Lengths  of  Three  Sizes  of 
Hose 91 

10.  Air  Quantities  Through  Floor  Brush  with  Various  Sizes 

and  Lengths  of  Hose,  Operated  on  Same  System  with 
Type  A  Renovators 92 

11.  Horse  Power  Required  at  Hose  Cock  to  Operate  Bare 

Floor  Brushes  on  Same  System  with  Type  A  Reno- 
vators         93 

12.  Free   Air  Passing  Brush   Type  of  Bare   Floor  Reno- 

vator Operated  on  Same  System  with  Type  C  Carpet 
Renovators    94 

13.  Horse  Power  at  Hose  Cock  with  Brush  Type  of  Bare 

Floor    Renovator    Operated    on    Same    System    with 

Type  C  Carpet  Renovators 94 

ix 


x  TABLES 

14.  Cubic  Feet  of  Free  Air  Passing  the  Felt-Covered  Floor 

Renovator  Operated  on  Same  System  with  Type  A 
Renovators    96 

15.  Horse  Power  Required  at  Hose  Cock  to  Operate  Felt- 

Covered  Floor  Renovators  Operated  on  Same  System 
with  Type  A  Renovators 96 

16.  Vacuum  at  Hose  Cock  with  2  in.  Vacuum  at  Type  A 

Renovator 97 

17.  Air  Quantities  when  Bristle  Bare  Floor  Renovators  are 

Used  in  Conjunction  with  Type  A  Carpet  Renovators 

at  2  in.  Mercury   98 

18.  Pipe   Sizes  Required,   as   Determined  by  Air  Passing 

Renovators    109 

19.  Friction  Loss  in  Pipe  Lines,  with   Carpet  Renovators 

in  Use  Exclusively 109 

20.  Pressure  Losses  from  Inlet  to  Separator  in  System  for 

Cleaning  Railroad  Cars    121 


ILLUSTRATIONS. 

FIG.  PAGE. 

1.  Early   Type   of    Mechanical    Cleaning    Nozzle    Using   Com- 

pressed Air    6 

2.  Another  Type  of  Compressed  Air  Cleaning  Nozzle,  Supple- 

mented with  Vacuum  Pipe 8 

3.  Separators  Used  With  Combined  Compressed  Air  and  Vacuum 

Machines    9 

4.  Piston  Type  of  Vacuum  Pump,  Mounted  Tandem  With  Air 

Compressor    9 

5.  Mr.   Kenney's  First  Renovator.   Vacuum  Alone  Being  Used 

as  Cleaning  Agent 10 

6.  Air  Compressors  Arranged  for  Operation  as  Vacuum  Pumps  n 

7.  Separators  Installed  by  Mr.  Kenney  in  Frick  Building 12 

8.  Vacuum    Renovator   With    Inrush    Slot,    Introduced    by   the 

Sanitary    Devices    Manufacturing   Company 13 

9.  First  Portable  Vacuum  Cleaner,  Constructed  by  Dr.  William 

Noe,  of  San  Francisco,   in   1905 • 16 

10.  Late  Type  of  Spencer  Vacuum  Cleaning  Machine,  Operated 

by   Multi-Stage   Turbine    Blowers    17 

1 1.  Type  A,  the   Straight  Vacuum   Tool 26 

12.  Type  B,  with  Wide  Slot  and  Wide  Bearing  Surface 26 

13.  Type  C,  with  Auxiliary  Slot,  Open  to  Atmosphere 28 

14.  Type  D,  with  Two  Cleaning  Slots   28 

15.  Type  E,  with  Inrush  Slot  on  Each  Side  of  Vacuum  Slot. ...  31 

16.  Type  F,  an  Exaggerated  Form  of  Type  B 31 

17.  Tests  of  Three  Renovators  on  Dirty  Carpets 35 

1 8.  Cleaning  Tests  of  Carpets  Filled  with  Quicksand 39 

19.  Cleaning  Tests   Using   I    oz.   of   Sand   Per   Square  Yard   of 

Carpet    41 

20.  Three  Series  of  Tests  with  Kenney  Type  A  Renovators 45 

21.  Tests  by  Mr.  Reeve,  Using  Type  C  Renovator 46 

22.  Tests  by  Mr.  Reeve,  Using  Type  D  Renovator 47 

23.  Tests  Showing  Efficiency  of  Different  Types  of  Renovators 

at  Different  Degrees  of  Vacuum 50 

24.  Early  Type  of  Bare  Floor  Renovator 55 

25.  Later  Type  of  Bare  Floor  Renovator 55 

26.  Another  Type  of  Bare  Floor  Renovator 56 

27.  Bare  Floor  Renovator  with  Felt  Cleaning  Surface 57 

28.  Bare  Floor  Renovator  with  Unusual   Form  of  Slot 58 

29.  Bare  Floor  Renovator  with  Hard  Felt  or  Composition  Rub- 

ber  Strips    58 

xi 


xii  ILLUSTRATIONS 

FIG.  PAGE. 

30.  Bare  Floor  Renovator  with  Rounded  Wearing  Surface 59 

3oa.  The  Tuec  School  Tool   62 

31.  Round  Bristle  Brush  for  Carved  or  Other  Relief  Work 62 

32.  Rubber-Tipped  Corner  Cleaner  for  Use  on  Carved  or  Other 

Relief  Work 62 

33.  Early  Type  of  Upholstery  Renovator 63 

34.  Upholstery  Renovator  with  Narrow  Slots  to  Prevent  Damage 

to   Furniture    64 

35.  Another  Type  of  Upholstery  Renovator  with  Short  Slots ...  65 

36.  Hand  Brush  Type  of  Renovator   65 

37.  Form  of  Swivel  Joint  Connecting  Stem  to  Renovator 72 

38.  Swivel  Joint  Arranged  to  Prevent  Dust  Lodging  Between  the 

Wearing  Surfaces    73 

39.  Swivel  Joint  in  Use 74 

40.  Another  Use  of  Swivel  Joint,   Showing   Possibilities   of   this 

Form    75 

41.  Operator  Cleaning  Trim  of  Door  with  Swivel  Joint 76 

42.  Swivel  Joint,  with  Screwed  Union   76 

43.  Swivel  Joint  Having  Ball  Bearings 76 

44.  Action  of  Bail-Bearing  Swivel  Joint 77 

45.  Illustration  of  Defects  of  Plug  Cocks 78 

46.  Bayonet  Type  of  Hose  Coupling,  Introduced  by  the  American 

Air  Cleaning  Company    82 

47.  All   Rubber   Hose   Coupling   Used   by   the   Spencer  .Turbine 

Cleaner    Company 83 

48.  Chart  for  Determining  Hose  Friction 86 

49.  Effect  of  Increase  of  Velocity  on  the  Friction  Loss 88 

50.  Another  Test  Showing  Friction  Loss  Due  to  Velocity 89 

51".  Inlet  Cock  to  Prevent  Air  Leakage  when  Not  in  Use 101 

52.  Type  of  Automatic  Self-Closing  Inlet  Cock 102 

53.  "Smooth  Bore"  Pipe  Coupling 103 

54.  Joint  Made  of  Standard  Pipe  Flanges 104 

55.  Standard    Durham    Recessed     Drainage     Fittings     Generally 

Used    in    Vacuum    Cleaning    Installations 105 

56.  Friction  Loss  in   Pipe   Lines 106 

57-60.  Diagrams   Showing  Operation  of   Brush   and  Carpet  Re- 
novators Under  Different  Conditions no 

61.  Typical  Floor  Plan  of  Office   Building  Illustrating  Number 

of  Sweepers  Required 114 

62.  Plan    of    Layout    for    Office    Building    Showing    Best    Loca- 

tion   (at  d)    for  Vacuum   Producer 118 

63.  Vacuum  Cleaning  Layout  for  a  Passenger  Car  Storage  Yard  122 

64.  Arrangement  of  Piping  Recommended  as  Best  for  Passenger 

Car   Storage   Yard    123 

65.  Good  Location  for  Dust  Separator  Where  Large  Areas  Are 

Served  by  One  Cleaning  System   125 


ILLUSTRATIONS  xiii 

FIG.  PAGE. 

66.  Location  of  Separators  at  Centers  of  Groups  of   Risers  for 

Large  Systems    126 

67.  Early  Type  of  Primary  Separator,  Used  by  Vacuum  Cleaner 

Company    128 

68.  Primary    Separator    Used    by    the    Sanitary    Devices    Manu- 

facturing  Company    128 

69.  Primary  Separator  Used  by  the  General  Compressed  Air  and 

Vacuum  Cleaning  Company    129 

70.  Primary  Separator  Made  by  the  Blaisdell  Engineering  Co...  129 

71.  Secondary  Separator  Used  by  the  Vacuum  Cleaner  Company  131 

72.  Secondary  Separator   Used  by  the   General  Compressed  Air 

and  Vacuum  Cleaning  Company   131 

73.  Secondary   Separator   Used  by  the   Sanitary  Devices    Manu- 

facturing Company    132 

74.  Type  of  Dry  Separator  Used  as  Secondary  Separator 134 

75.  Form  of  Complete  Separator  Used  by  the  Vacuum  Cleaner 

Company    '. 135 

76.  Complete  Separator  Brought  Out  by  the  Electric  Renovator 

Manufacturing    Company    136 

77.  Complete  Separator  Made  by  the  American  Radiator  Company  137 
773.  Interior  Construction  of  Dunn  Vacuum  Cleaning  Machine  140 

78.  Power  Consumption  and  Efficiency  of  Air  Compressor  Used 

as  a  Vacuum  Pump 143 

79.  Modification  of  Reciprocating  Pump   Made  by   the  Sanitary 

Devices  Manufacturing  Company    144 

80.  Power  Consumption  and  Efficiency  of  Modified  Reciprocating 

Pump    145 

81  and  82.  Indicator  Cards  for  Clayton  and  Modified  Pumps.  ..  .      146 

83.  One  of  the  Pumps  Installed  in  Connection  with  the  Vacuum 

Cleaning   System    in    the    New   York    Post     Office,     the 
Largest  Reciprocating  Pump  Used  for  this  Purpose  up  to  ^ 
the  Present   148 

84.  Interior  Arrangement  of  the  Garden  City  Rotary  Pump....      149 

85.  Power   Required   to  Operate   Garden   City  Type  of   Rotary 

Pump 150 

86.  Arrangement  of  Double-Impeller  Root  Type   Rotary  Pump 

for  Vacuum  Cleaning  Work   I51 

87.  Rotary  Pump  Arranged  with  Double-Throw  Switch  for  Re- 

versing Pump   1 52 

88.  Power  Consumption  and  Efficiency  of  Root  Type  of  Pump..      153 

89.  The  Rotrex  Vacuum  Pump,  Used  by  the  Vacuum  Engineer- 

ing  Company    153 

90.  Late  Type  of  Centrifugal  Exhauster  Made  by  the  Spencer 

Turbine  Cleaner  Company 154 

91.  Power  and  Efficiency  Curves  for  the  Spencer  Machine 155 


xiv  ILLUSTRATIONS 

FIG.  PAGE. 

92.  Interior  Arrangement  of  Invincible  Machine,   Manufactured 

by  the  Electric  Renovator   Manufacturing  Company....      156 

93.  Power  Consumption,  Vacuum  and  Efficiency  of  First  Types 

of  Invincible   Machine    157 

94.  Power    Consumption,    Vacuum    and    Efficiency    of    Invincible 

Machine  After  Valve  Was  Fitted  to  Discharge 158 

95.  Four-Sweeper  Invincible  Plant  Installed  in  the  United  States 

Post  Office  at  Los  Angeles,  Cal 159 

96.  Centrifrugal   Pump  with   Single   Impeller,   Manufactured  by 

by  The  United  Electric  Company  161 

963.  Test  of  Centrifugal  Pump  with  Single   Impeller 162 

97.  Steam  Aspirator  Used  by  the  American  Air  Cleaning  Company  163 

98.  Steam  Consumption  of  Steam  Aspirator 164 

99.  First   Type   of   Controller    Introduced   by   the   Sanitary   De- 

vices  Manufacturing   Company,   known   as  the  "Unload- 
ing Valve" 167 

100.  Test  of  Controller  Connected  to  Suction  of  8-Sweeper  Piston 

Pump 168 

101.  Type  of  Controller  for  Use  on  Pumps  Without  Valves 169 

102.  Regulator  for  Motor-Driven  Vacuum  Pump,   Manufactured 

by  the  Cutler-Hammer  Manufacturing  Company 170 

103.  Inspirator  Type  Vacuum  Contactor,  Used  to  Control   Pilot 

Motor  of  Cutler-Hammer  Controller 171 

104.  Vacometer  for  Use  in  Testing  Vacuum  Cleaning  Systems...      190 


PREFACE. 

The  contents  of  this  work  are  compiled  from  the  observations 
of  the  author  through  the  seven  years  during  which  he  has 
been  engaged  in  the  preparation  of  specifications  for,  and  the 
testing  of,  complete  plants  installed  in  the  buildings  under  the 
control  of  the  Treasury  Department. 

During  this  time  it  has  become  necessary  to  alter  no  less  than 
five  times  the  stock  form  of  specifications  for  stationary  vacuum 
cleaning  plants  which  were  adopted  by  the  Government,  with 
the  intent  of  obtaining  the  widest  competition  possible  with 
efficient  and  economical  operation,  in  order  to  keep  pace  with 
the  variation  and  improvement  in  the  apparatus  manufactured. 
As  each  new  type  of  system  has  come  on  the  market  a  personal 
investigation  at  the  factory,  together  with  tests,  has  been  made. 
An  exhaustive  test  of  carpet  renovators  was  also  conducted, 
using  one  of  the  Government  plants.  In  addition  the  vaco- 
meters  recommended  for  use  in  capacity  tests  were  carefully 
calibrated,  using  the  machine  at  the  Department  of  Agriculture. 

The  writer  wishes  to  acknowledge  the  aid  received  from  the 
various  manufacturers  in  furnishing  illustrations  and  data  on 
their  machines,  to  Messrs.  Ewing  &  Ewing  and  Prof.  Sidney  A. 
Reeve  for  data  on  tests  made  by  Prof.  Reeve  and  used  in  de- 
fending the  Kenney  basic  patent. 

In  analyzing  the  results  of  his  tests  and  observations,  the 
writer  has  endeavored  to  put  his  own  conclusions  into  concrete 
form  for  the  use  of  the  consulting  engineer  and  has  not  entered 
into  the  problems  to  be  encountered  in  the  design  and  manu- 
facture of  the  various  forms  of  apparatus. 


CHAPTER  I. 
HISTORY  OF  MECHANICAL  CLEANING. 

Early  Attempts. — Whenever  machinery  has  been  introduced 
to  assist  or  replace  manual  labor,  the  earlier  attempts  have  been 
in  imitating  the  tools  formerly  used  by  man.  As  the  earliest 
mechanically-propelled  carriages  were  mechanical  walking  ma- 
chines, the  earliest  steamboats  mechanical  rowing  machines, 
and  the  earliest  flying  machines  mechanical  birds,  so  were  the 
earliest  mechanical  cleaners  in  the  form  of  mechanical  brooms. 

These  mechanical  brooms  were  introduced  about  1880  and 
took  the  form  of  the  well-known  street  sweeper,  with  a  large 
circular  brush  mounted  on  a  four-wheeled  cart  and  rotated  by 
means  of  gearing  driven  from  the  wheels,  the  propelling  power 
being  the  horses  which  drew  the  machine. 

This  machine  at  once  made  itself  unpopular  with  the  resi- 
dents of  the  streets  cleaned  on  account  of  its  great  activity  in 
stirring  up  dust,  because  the  streets  were  swept  dry.  This 
trouble  was  later  overcome  to  a  considerable  extent  by  sprink- 
ling the  streets  before  sweeping,  but  only  at  a  sacrifice  in 
efficiency  of  cleaning,  especially  where  such  uneven  surfaces 
as  cobble  or  medina  stone  blocks  formed  the  surface  of  the 
roadway.  Various  attachments  were  added  to  reduce  this  dust 
nuisance,  but  none  has  apparently  been  successful,  as  we  see 
these  machines  in  their  original  form  in  use  today. 

Almost  simultaneously  with  the  introduction  of  the  street 
sweeper  came  its  counterpart,  the  carpet  sweeper,  with  a  similar 
but  smaller  brush,  enclosed  in  a  wood  and  metal  case,  the 
brush  being  driven  by  friction  from  the  wheels  supporting  the 
box  and  the  power  for  operation  being  derived  from  the  person 
who  pushed  the  machine  along  the  floor. 

This  machine  has  not  been  modified  to  any  great  extent  dur- 
ing the  thirty  odd  years  of  its  existence.  It  is  today  in  prac- 

3 


4  VACUUM    CLEANING    SYSTEMS 

tically  its  original  form,  and  is  doing  no  better  work  than  when 
first  introduced.  This  form  of  mechanical  cleaner  occupied  the 
field  of  household  cleaning  for  nearly  twenty  years  without  a 
rival,  during  which  time  it  won  its  way  into  the  hearts  and 
hands  of  many  housekeepers  in  this  and  other  countries. 

Limitations  of  the  Carpet  Sweeper. — This  device,  with  its 
light  brush  and  equally  light  pressure  on  the  surface  cleaned 
and  its  limited  capacity  for  carrying  the  material  picked  up, 
has  never  been  a  thorough  cleaner  in  any  sense  of  the  word, 
and  has  been  and  is  now  used  only  to  take  up  that  portion  of 
the  usual  litter  and  light  dust  which  is  located  directly  on  the 
surface,  and  is,  therefore,  most  annoying  to  the  housekeeper, 
owing  to  its  being  visible  to  the  eye.  Because  of  its  generous 
proportions,  made  necessary  to  accommodate  the  material 
picked  up,  and  its  centrally-pivoted  handle,  made  necessary 
by  its  mechanical  construction,  it  is  impossible  to  operate  it 
under  low  furniture.  Like  the  lawn  mower,  it  must  be  in 
motion  in  order  to  operate  its  revolving  brush,  on  which  its 
cleaning  action  is  dependent.  It  is  impossible  to  make  use  of 
same  in  corners,  along  walls,  or  close  to  heavy  furniture,  its 
use  being  limited  to  a  literal  slicking  up  of  those  portions  of 
the  carpet  in  the  most  conspicuous  portions  of  the  apartment. 
In  spite  of  these  serious  defects  it  came  into,  and  is  still  in, 
nearly  universal  use,  even  in  households  equipped  with  the 
latest  approved  types  of  mechanical  cleaners.  Its  use  on  bare 
floors  has  never  been  even  a  moderate  success  and  in  no  case 
has  it  superseded  the  broom  and  dust  pan  of  our  grandmothers 

Compressed  Air  Cleaners. —  Compressed  air  has  been  in  use 
for  many  years  in  foundries  and  machine  shops,  for  cleaning 
castings  and  producing  certain  finishes  on  metal.  With  the 
introduction  of  modern  electrical  machinery  it  was  rapidly 
adapted  to  the  cleaning  of  windings  and  other  inaccessible  parts 
of  this  machinery.  Its  first  use  in  cleaning  buildings  was  un- 
doubtedly in  the  form  of  an  open  jet  for  dislodging  dust  from 
carvings  and  relief  work,  for  which  purpose  it  is  very  efficient 
as  a  remover  of  the  dust  from  the  parts  to  be  cleaned  and  also 
as  a  distributor  of  this  same  dust  over  the  widest  possible  area 
for  subsequent  removal  by  other  means.  It  has  a  draw-back 
in  that  the  expansion  of  air  both  cools  the  same  and  reduces 


HISTORY  OF  MECHANICAL  CLEANING  5 

its  ability  to  retain  moisture,  resulting  in  the  deposit  of  mois- 
ture on  the  surfaces  cleaned. 

About  1898,  attempts  to  overcome  the  objections  to  the  open 
air  jet  and  to  produce  a  commercially  successful  compressed 
air  carpet  cleaner  were  undertaken  almost  simultaneously  by 
two  companies,  the  American  Air  Cleaning  Company,  of  Mil- 
waukee, operating  under  the  Christensen  patents,  and  the 
General  Compressed  Air  Cleaning  Company,  of  St.  Louis,  oper- 
ating under  the  Thurman  patents. 

The  renovator  used  by  the  American  Air  Cleaning  Com- 
pany consisted  of  a  heavy  metal  frame,  about  18  in.  long  and 
12  in.  wide,  having  mounted  on  its  longer  axis  a  wedge-like 
nozzle  extending  the  entire  length  of  the  frame,  with  a  very 
narrow  slit,  1/64  in.  wide,  extending  the  entire  length  of  its 
lower  edge.  This  nozzle  was  pivoted  and  so  connected  to  the 
operating  handle,  by  which  the  renovator  was  moved  over  the 
floor,  that  when  the  renovator  was  alternately  pushed  and 
pulled  over  the  surface  to  be  cleaned,  the  slot  was  always 
inclined  in  the  direction  in  which  the  renovator  was  being- 
moved.  The  top  of  the  renovator  was  closed  by  a  canvas  bag, 
smaller  at  the  neck  than  in  its  center,  which  was  supported  by 
a  wire  hook. 

Air  was  introduced  into  the  nozzle,  at  a  pressure  of  from 
45  to  55  Ibs.  per  square  inch,  and  issued  from  the  slot  in  a  thin 
sheet  which  impinged  on  the  carpet  at  an  angle.  The  frame 
was  held  close  to  the  carpet  by  its  weight,  preventing  the 
escape  of  the  air  under  its  lower  edge.  The  air  striking  the 
carpet  at  an  angle  was  deflected  up  into  the  bag,  inflating 
same  like  a  miniature  balloon.  The  dust  loosened  from  the 
carpet  by  the  impact  of  the  air  was  carried  up  into  the  bag 
where  it  lodged,  the  air  escaping  through  the  fabric  of  the 
canvas  into  the  apartment. 

The  renovator  used  by  the  General  Compressed  Air  Clean- 
ing Company  differed  from  the  above-described  renovator  in 
that  it  contained  two  nozzles,  with  slots  inclined  at  fixed  angles 
to  the  carpet.  A  pair  of  hand-operated  valves  were  provided 
in  the  handle  to  introduce  air  into  the  nozzle  which  was  inclined 
in  the  direction  in  which  the  renovator  was  moving;  other- 


6 


VACUUM  CLEANING  SYSTEMS 


wise  the  renovator  was  identical  with  that  used  by  the  Mil- 
waukee company. 

These  renovators  were  generally  supplied  with  air  from  a 
portable  unit,  consisting  of  an  air  compressor,  driven  by  a  gaso- 
line engine  mounted  with  the  necessary  gasoline  and  air  storage 
tanks  on  a  small  truck.  One  of  these  machines  was  in  use  in 
Washington  last  year,  but  its  use  at  that  time  was  very  limited 
and  it  is  not  to  be  seen  this  year. 

These  trucks  were  drawn  up  in  front  of  the  building  to  be 
cleaned  and  a  large-size  hose,  usually  1^4  in.  in  diameter,  was 
carried  into  the  house  and  attached  to  an  auxiliary  tank  from 
which  y2  -in.  diameter  hose  lines  were  carried  to  two  or  more 
renovators. 

A  few  buildings  were  equipped  with  air  compressors  and 
pipe  lines,  with  outlets  throughout  the  building  for  use  with 
this  type  of  renovator,  among  which  was  the  Hotel  Astor  in 
New  York  City. 

These  renovators,  the  construction  of  which  is  shown  diagram- 
matically  in  Fig.  1,  required  approximately  35  cu.  ft.  of  free 


FIG.   I. 


EARLY  TYPE   OF   MECHANICAL   CLEANING   NOZZLE 
USING   COMPRESSED   AIR. 


air  per  minute  at  a  pressure  of  from  45  to  53  Ibs.  per  square 
inch  and  were  usually  driven  by  a  15  H.  P.  engine. 

The  renovators  were  very  heavy  to  carry  about,  although 
their  operation  with  the  air  pressure  under  them  was  not 
difficult.  However,  their  operation  was  complicated,  requiring 


HISTORY  OF  MECHANICAL  CLEANING  7 

skilled  operators.  Owing  to  their  generous  proportions  it  was 
impossible  to  clean  around  furniture,  making  its  removal  from 
the  apartment  necessary,  and  limiting  their  use  to  the  cleaning 
of  carpetts  at  the  time  of  general  house  cleaning.  The  cooling 
effect  of  the  expansion  of  the  air  in  the  nozzle  often  caused 
condensation  of  moisture  on  the  carpets  when  the  relative 
humidity  was  high.  They  were  also  at  a  disadvantage  in  that 
all  the  heavy  dust  collected  in  the  canvas  bag  had  to  be  carried 
from  the  apartment  by  hand.  Owing  to  the  constant  agitation 
of  the  dust  in  the  bag  by  the  entering  air  currents,  much  of 
the  finer  particles  of  dust  and  all  the  disease  germs  liberated 
by  the  renovator  were  blown  through  the  bag  back  into  the 
apartment.  They  were  not,  therefore,  by  any  means  sanitary 
devices. 

Vacuum  Produced  by  Compressed  Air. — The  General  Com- 
pressed Air  Cleaning  Company  also  introduced  another  form  of 
renovator  for  use  with  their  compressed  air  plants.  This  was 
composed  of  an  ejector  operated  by  compressed  air,  with  a 
short  hose  attached  to  a  carpet  renovator  of  the  straight  nar- 
row-slot type,  such  as  was  used  later  in  vacuum  cleaning  sys- 
tems. The  outlet  from  this  ejector  was  connected  by  another 
short  hose  to  a  metal  box  containing  a  canvas  bag,  woven  back- 
wards and  forwards  over  metal  frames  to  give  a  large  surface 
for  the  passage  of  air.  The  dust  picked  up  by  the  suction  of 
the  ejector  was  carried  with  the  air  into  the  box  and  there 
separated  from  the  air,  which  escaped  through  the  canvas  into 
the  apartment. 

This  form  of  renovator  overcame  some  of  the  objections  to 
the  former  type  in  that  there  was  no  condensation  of  moisture 
on  the  carpets,  and  it  was  possible  to  operate  the  renovator 
under  and  around  furniture,  and  even  on  portieres  and  other 
hangings.  However,  the  apparatus  was  rendered  inefficient 
by  the  resistance  of  the  bag,  causing  a  back  pressure  on  the 
injector  which  greatly  reduced  its  air-drawing  capacity. 

Compressed  Air  Supplemented  by  Vacuum. — Shortly  after 
these  two  companies  began  operation,  the  Sanitary  Devices 
Manufacturing  Company,  of  San  Francisco,  introduced  a  new 
system  of  mechanical  cleaning  under  the  Lotz  patents.  This 


8  VACUUM    CLEANING    SYSTEMS 

system  used  a  renovator  having  a  compressed  air  nozzle  ter- 
minating in  a  narrow  slot,  similar  to  the  nozzles  of  the  Amer- 
ican and  Thurman  systems,  but  differing  from  them  in  that 
the  slot  was  fixed  vertically,  pointing  downward.  This  nozzle 
was  surrounded  by  an  annular  chamber  having  an  opening  at 
the  bottom  of  considerable  width.  The  whole  formed  a  reno- 
vator about  14  in.  long  and  not  over  2  in.  wide  at  its  base.  In 
addition  to  the  compressed  air  connection  to  its  nozzle,  a  second 
hose,  1  in.  in  diameter,  was  connected  to  the  annular  space 
surrounding  the  nozzle  and  led  to  a  vacuum  pump  by  which 
the  air  liberated  through  the  nozzle,  together  with  the  dust 
which  "was  liberated  from  the  carpet,  was  carried  from  the 
apartment.  The  construction  of  this  renovator  is  shown  dia- 
grammatically  in  Fig.  2. 


Vacuum-  ~  ~/^  Air, 


FIG.    2.      ANOTHER    TYPE    OF    COMPRESSED    AIR    CLEANING 
NOZZLE,   SUPPLEMENTED  WITH  VACUUM   PIPE. 

As  dust-laden  air  was  not  suitable  to  be  carried  through  the 
pump  used  as  a  vacuum  producer,  separators  had  to  be  pro- 
vided to  remove  the  dust  from  this  air  before  it  reached  the 
pump.  The  separators  used  consisted  of  two  cylindrical  tanks. 
The  air  was  introduced  into  the  first  tank  in  such  a  way  that 
a  whirling  motion  was  imparted  to  it,  thus  separating  the 
heavier  particles  of  dust  by  centrifugal  force.  The  second 
tank  contained  water  which  was  brought  into  intimate  contact 
with  the  air  by  means  of  an  atomizer  located  in  the  pipe  con- 
nection between  the  two  tanks,  thus  washing  the  air  in  a  man- 
ner somewhat  similar  to  the  familiar  air  washers  used  in  con- 
nection with  mechanical  ventilating  systems.  The  air  and 
spray  then  entered  the  second  tank,  above  the  water  line,  where 


HISTORY  OF  MECHANICAL  CLEANING  9 

the  entrained  water  separated  on  the  reduction  of  velocity  and 
fell  back  into  the  water  below,  to  be  recirculated  through  the 


FIG.  3.   SEPARATORS  USED  WITH  COMBINED  COMPRESSED  AIR 
AND  VACUUM  MACHINES. 

atomizer.     The  air  passed  on  out  of  the  top  of  the  tank  to  the 
pump.    An  illustration  of  these  separators  is  shown  in  Fig.  3, 
Piston   Pump  the   First   Satisfactory  Vacuum   Producer.— 
Various  types  of  apparatus  were  tried  as  vacuum  producers, 
including  an  air  ejector,  such  as  was  used  with  the  Thurman 


Vacuum  Discharge--'  Compressor  In  take-1 


FIG     4       PISTON    TYPE    OF    VACUUM    PUMP,    MOUNTED    TANDEM 
WITH    AIR    COMPRESSOR. 


10  VACUUM    CLEANING    SYSTEMS 

renovator,  and  found  to  be  ineffective  due  to  its  inability  to 
overcome  the  back-pressure  necessary  to  discharge  the  air 
through  the  hose,  which  was  placed  on  its  outlet.  A  rotary 
pump  was  next  tried,  but,  owing  to  the  selection  of  an  in- 
efficient type,  this  was  abandoned  and,  finally,  a  piston-type 
vacuum  pump,  with  very  light  poppet  valves  and  mounted  tan- 
dem with  the  air  compressor,  was  adapted  and  remained  in  use 
with  this  system  until  straight  vacuum  was  adopted,  when  the 
air  compression  cylinder  was  omitted.  This  pump  is  illus- 
trated in  Fig.  4. 


FIG.    5.      MR.    KENNEY'S    FIRST    RENOVATOR,    VACUUM    ALONE 
BEING    USED   AS   CLEANING   AGENT. 

In  this  system  we  see  the  first  sanitary  device  to  be  intro- 
duced into  the  field  of  mechanical  cleaning,  as  the  dust  and 
germ-laden  air  were  removed  entirely  from  the  apartment  and 
purified  before  being  discharged  into  the  outside  atmosphere. 
The  foulness  of  the  water  in  the  separators  clearly  showed  the 
amount  of  impurities  removed  from  the  air. 


HISTORY  OF  MECHANICAL  CLEANING 


11 


These  machines  were  mounted  on  wagons,  similar  to  their 
forerunners,  and  were  also  installed  in  many  buildings  as 
stationary  plants,  among  which  were  the  old  Palace  Hotel  and 
the  branch  Mint,  in  San  Francisco,  and  the  old  Fifth  Avenue 
Hotel,  in  New  York  City. 

Systems  Using  Vacuum  Only. — In  1902  David  T.  Kenney, 
of  New  York,  installed  the  first  mechanical  cleaning  system  in 
which  vacuum  alone  was  used  as  the  cleaning  agent.  Mr. 
Kenney  used  a  renovator  with  a  slot  about  12  in.  long  and  3/16 
in.  wide,  attached  to  a  metal  tube  which  served  as  a  handle, 


I 


FIG. 


AIR    COMPRESSORS     ARRANGED     FOR    OPERATION    AS 
VACUUM    PUMPS. 


and  to  a  ^-m.  diameter  hose  and  larger  pipe  line  leading  to 
separators  and  vacuum  pump.  Mr.  Kenney 's  first  renovator  is 
illustrated  in  Fig.  5. 

Mr.  Kenney  used  as  vacuum  pumps  commercial  air  com- 
pressors, the  first  of  which  was  installed  in  the  Frick  Building 
in  1902  and  is  illustrated  in  Fig.  6.  Later  he  adapted  the  Clay- 


12 


VACUUM    CLEANING    SYSTEMS 


ton  air  compressor,  with  mechanically-operated  induction  and 
poppet  eduction  valves  on  larger  sizes,  and  single  mechanically- 
operated  induction  and  eduction  valves  on  the  smaller  sizes. 

The  separators  used  by  Mr.  Kenney  differed  from  those  used 
by  the  Sanitary  Devices  Manufacturing  Company  in  that  they 
contained  several  interior  partitions,  screens,  and  baffles,  and 


FIG.    7.      SEPARATORS    INSTALLED    BY    MR.    KENNEY    IN    FRICK 
BUILDING. 


the  air  was  drawn  directly  through  the  body  of  water  in  the 
wet  separator.  The  relative  merits  of  these  types  of  separators 
will  be  discussed  in  a  later  chapter. 

The  separators  installed  by  Mr.  Kenney  in  the  Frick  Build- 
ing, and  which  are  practically  the  same  as  were  used  by  him 


HISTORY  OF  MECHANICAL  CLEANING 


13 


as  long  as  he  manufactured  vacuum  cleaning  apparatus,  are 
illustrated  in  Fig.  7. 

After  his  application  had  been  in  the  patent  office  for  about 
six  years  he  was  granted  a  fundamental  patent  on  a  vacuum 
cleaning  system. 

Renovator  with  Inrush  Slot. —  The  Sanitary  Devices  Manu- 
facturing Company  then  produced  a  carpet  renovator  using 
vacuum  only  as .  a  cleaning  agent.  This  cleaner  has  a  wider 
cleaning  slot  that  the  cleaners  usually  furnished  by  Mr.  Kenney, 
about  5/16  in.  wide,  with  a  supplemental  slot  or  vacuum  breaker 
opening  out  of  the  top  of  the  renovator  and  separated  from  the 
cleaning  slot  by  a  narrow  partition  extending  nearly  to  the 


•-25 


-Pile  of  Carpet 

^•Back of 'Carpet 
•Floor 


FIG.    8.      VACUUM   RENOVATOR   WITH   INRUSH  SLOT,    INTRODUCED 
BY  THE  SANITARY  DEVICES  MANUFACTURING  CO. 


carpet,  as  illustrated  in  Fig.  8.     The  relative  merits  of  these 
types  of  renovators  will  be  discussed  in  a  later  chapter. 

Shortly  after  the  introduction  of  vacuum  cleaning  by  Mr. 
Kenney  and  the  Sanitary  Devices  Manufacturing  Company,  the 
American  Air  Cleaning  Company  published  an  interesting  little 
booklet  entitled,  "Compressed  Air  Versus  Vacuum,"  which  set 
forth  in  great  detail  the  so-called  advantages  of  compressed  air 
over  vacuum  as  a  medium  of  mechanical  carpet  cleaning,  and, 
apparently,  proved  that  vacuum  cleaners  were  much  less  effi- 
cient than  cleaners  operated  by  compressed  air.  A  year  or  two 
later  the  American  Air  Cleaning  Company  evidently  had  a 
change  of  heart  and  began  to  manufacture  these  same  "in- 


14  VACUUM    CLEANING    SYSTEMS 

efficient"  vacuum  cleaners.  Their  previous  treatise  on  vacuum 
cleaning,  which  apparently  was  not  copyrighted,  was  repub- 
lished  by  both  the  Sanitary  Devices  Manufacturing  Company 
and  by  the  Vacuum  Cleaner  Company,  which  had  acquired 
Mr.  Kenney's  patents,  and  freely  distributed.  Thus  this  little 
work  of  the  Milwaukee  company,  instead  of  injuring  their 
competitors,  was  turned  into  good  advertising  for  them  and 
required  a  lot  of  explanation  from  the  Milwaukee  company. 

Steam  Aspirators  Used  as  Vacuum  Producers. — The  Amer- 
ican Air  Cleaning  Company  used  a  steam  aspirator  as  its 
vacuum  producer  and,  unlike  its  predecessor,  the  air-operated 
ejector,  it  made  good  and  has  also  been  used  to  a  limited  extent 
by  the  Sanitary  Devices  Manufacturing  Company.  It  is  now 
marketed  by  the  Richmond  Radiator  Company,  and  its  merits 
will  be  discussed  in  a  later  chapter.  The  American  Air  Cleaner 
Company  also  used  as  a  vacuum  producer  the  single-impeller 
type  of  rota.ry  pump,  made  by  the  Garden  City  Engineering 
Company,  which  was  also  later  adopted,  to  a  limited  extent,  by 
the  Vacuum  Cleaner  Company.  This  will  be  discussed 
further  on. 

The  renovator  used  by  this  company  was  a  single-slot  type, 
with  %-in.  by  10-in.  cleaning  slot.  These  systems  at  once  be- 
came notable  on  account  of  the  small  size  of  the  vacuum  pro- 
ducers used,  the  low  degree  of  vacuum  carried,  and  the  vigorous 
campaign  of  advertising  which  was  conducted. 

Several  firms  soon  began  to  market  vacuum  cleaning  systems 
almost  identical  with  that  of  Mr.  Kenney,  among  which  were 
the  Blaisdell  Machinery  Company,  The  Baldwin  Engineering 
Company,  and  The  General  Compressed  Air  and  Vacuum 
Machinery  Company,  the  latter  being  the  original  Thurman 
company. 

The  Vacuum  Cleaner  Company  then  began  a  series  of  in- 
fringment  suits  against  nearly  every  manufacturer  of  vacuum 
cleaning  systems.  In  nearly  every  case  the  suit  has  resulted 
in  the  offending  company  paying  license  fees  to  the  Vacuum 
Cleaner  Company,  and  this  concern  has  now  abandoned  the 
manufacture  of  vacuum  cleaners  and  has  become  a  licensing 
company.  At  this  writing  nearly  twenty  firms  are  paying 


HISTORY  OF  MECHANICAL  CLEANING  15 

license  fees  to  the  Vacuum  Cleaner  Company  and  there  is  one 
suit  now  in  the  courts. 

Piston  Pump  Used  Without  Separators. —  A  vacuum  clean- 
ing system  of  somewhat  different  design  was  produced  by  two 
former  employees  of  the  Vacuum  Cleaner  Company,  Mr.  Dunn, 
the  once  well-known  " Farmer  Dunn"  of  the  weather  bureau, 
afterward  salesman  for  the  Vacuum  Cleaner  Company,  and  Mr. 
Locke,  at  one  time  this  firm's  engineer.  This  company  was 
first  known  as  the  Vacuum  Cleaning  Company,  and,  shortly 
afterward,  as  the  Dunn-Locke  Vacuum  Cleaning  Company.  No 
separators  were  used  with  this  system,  but  the  dust-laden  air 
was  led  from  the  pipe  lines  directly  into  a  chamber  on  the 
pump,  known  as  the  ''saturation  chamber,"  and  there  mingled 
with  a  stream  of  water  converting  the  dust  into  a  thin  mud. 
The  air,  water  and  mud  then  passed  through  the  pump,  the 
muddy  water  was  discharged  into  the  sewer,  and  the  air  into 
the  atmosphere.  The  vacuum  producer  used  was  a  piston  pump 
without  suction  valves.  With  this  system  it  was  possible  to 
handle  water  in  almost  unlimited  quantities  and  with  this  fea- 
ture a  system  of  mechanical  scrubbing  was  attempted  for  which 
great  claims  were  made,  none  of  which,  however,  were  realized 
in  a  commercial  way. 

These  gentlemen  sold  their  patents  to  the  E.  H.  Wheeler 
Company,  which  attempted  to  market  the  system  in  its  original 
form.  It  was  found,  however,  that  the  piston  pump  was  not 
adapted  to  the  handling  of  grit  which  was  picked  up  by  the 
renovators,  and  a  rotary  pump,  with  single  impeller  and  a  fol- 
lower was  substituted.  This  system  is  now  marketed  by  the 
Vacuum  Engineering  Company,  of  New  York,  and  is  known  as 
the  Eotrex  system. 

Mr.  Dunn  again  entered  the  field  of  vacuum  cleaning  and 
began  marketing  his  machine  a  short  time  ago  with  a  new  form 
of  'automatic  separator  discharging  to  sewer.  • 

First  Portable  Vacuum  Cleaner. —  About  1905,  Dr.  William 
Noe?  of  San  Francisco,  constructed  the  first  portable  vacuum 
cleaner.  This  machine  contained  a  mechanically-driven  rotary 
brush,  similar  to  the  brushes  used  in  the  familiar  carpet  sweeper, 
for  loosening  the  dust  from  the  carpet.  This  dust  was  sucked 
up  by  a  two-stage  turbine  fan  and  discharged  into  a  dust  bag, 


16  VACUUM    CLEANING    SYSTEMS 

mounted  on  the  handle,  similar  to  the  bags  on  the  compressed 
air  cleaners.  The  whole  machine  was  mounted  on  wheels  and 
provided  with  a  small  direct-connected  motor.  This  machine  is 
illustrated  in  Fig.  9  and  is  the  original  form  of  the  well-known 
Invincible  renovator  manufactured  by  the  Electric  Renovator 
Company,  of  Pittsburgh.  This  company  now  produces  a  com- 
plete line  of  stationary  and  portable  vacuum  cleaners,  all  of 
which  use  multi-stage  turbines.  The  sale  of  the  product  of  this 
company,  until  recently,  was  controlled  by  the  United  States 
Radiator  Corporation. 


FIG.  9.      FIRST  PORTABLE  VACUUM  CLEANER,  CONSTRUCTED  BY 
DR.  WILLIAM  NOE,  OF  SAN   FRANCISCO,   IN  1905. 

First  Use  of  Stationary  Multi-Stage  Turbine  Blowers. — 
About  1905  Mr.  Ira  Spencer,  president  and  engineer  of  the 
Organ  Power  Company,  which  manufactured  a  multi-stage  tur- 
bine blower  for  organs,  known  as  the  "Orgoblow,"  organized 
the  Spencer  Turbine  Cleaner  Company  and  marketed  a  vacuum 
cleaning  system,  using  a  modification  of  the  "Orgoblow"  as  a 
vacuum  producer.  These  machines  were  first  constructed  with/ 


HISTORY   OF   MECHANICAL    CLEANING 


17 


sheet  metal  casings  and  had  sheet  steel  fans,  with  wings  riveted 
on  and  mounted  on  horizontal  shafts.  The  separators  were  sheet 
metal  receptacles  with  screens  for  catching  litter.  Light-weight 
hose,  2  in.  in  diameter,  was  used  to  connect  the  renovators  to 
4-in.  sheet  metal  pipe  lines.  A  variety  of  renovators  was  pro- 
duced for  use  with  this  system.  Carpet  renovators  having 


- J/  "Square 


FIG.  10.      LATE  TYPE  OP  SPENCER  VACUUM  CLEANING  MACHINE, 
OPERATED  BY  MULTI-STAGE        TURBINE   BLOWER. 

cleaning  slots  varying  from  10  in.  by  ^4  in.  to  20  in.  by  l/^  in. 
were  used,  and  a  very  complete  line  of  swivel  joints  for  con- 
necting the  renovators  and  the  hose  to  the  handles  was  de- 
veloped. This  system  was  operated  at  5  in.  vacuum,  which  was 
much  lower  than  that  used  by  any  other  system,  15  in.  being 
standard  at  that  time,  and  a  much  larger  volume  of  air  was 


18  VACUUM    CLEANING    SYSTEMS 

exhausted  under  certain  conditions  than  was  possible  with  any 
of  the  then  existing  systems.  Owing  to  the  large  volume  of  air 
exhausted  and  to  the  large  size  of  the  renovators,  hose  and  pipe 
lines,  larger  articles  could  be  picked  up  than  was  possible  with 
any  of  the  existing  systems.  A  great  deal  of  weight  was 
attached  to  this  condition  by  the  manufacturers,  a  favorite 
stunt  being  to  pick  up  nails,  washers,  waste,  small  pieces  of 
paper  and  even  pea  coal  from  a  floor  and  finally  to  pick  up  a 
quantity  of  flour  which  had  first  been  carefully  arranged  for 
the  demonstration. 

This  invasion  of  the  vacuum  cleaning  field  was  considered  by 
the  established  manufacturers  as  a  freak  and  the  apparatus 
was  christened  "the  tin  machine."  Whenever  it  was  in- 
stalled in  competition  with  other  forms  of  cleaning  systems, 
the  daily  question  asked  by  its  competitors  was,  "Has  the  tin 
machine  fallen  apart?"  However,  the  tin  machine  did  not  fall 
apart,  but  held  its  own  with  the  other  systems,  even  in  its 
crude  and  inefficient  state.  Finding  that  the  construction  he 
had  adopted  was  too  flimsy  and  subject  to  abnormal  leakage, 
Mr.  Spencer  developed  a  new  form  of  machine,  using  cast-iron 
casing  and  welded  fan  wheels  and  adopted  standard  pipe  and 
fittings.  He  also  brought  out  a  line  of  sheet  metal  tools  and 
on  the  whole  perfected  a  satisfactory  cleaning  system.  One  of 
his  machines  of  a  later  type  is  illustrated  in  Fig.  10. 

Separators  Emptying  to  Sewer  by  Air  Pressure. — A  new 
form  of  vacuum  cleaning  system  was  introduced  by  Mr.  Moor- 
head,  of  San  Francisco,  who  used  an  inrush  type  of  renovator 
having  an  inlet  for  air  on  each  side  of  the  cleaning  slot. 

The  separator  used  with  this  system  was  a  wet  separator  and 
contained  a  screen  cleaned  by  a  rotary  brush  into  which  all 
the  dust  contained  in  the  air  lodged.  The  pump  used  with  this 
system  was  generally  of  the  piston  type,  fitted  with  a  single 
rotary  valve,  so  connected  to  the  valve  stem  that  it  could  be 
rotated  thereon  and  the  machine  changed  from  a  vacuum  pump 
to  an  air  compressor  in  order  that  the  contents  of  the  separators 
might  be  discharged  into  the  sewer  by  air  pressure  when  it 
was  desired  to  empty  same. 

This  system  was  marketed  by  the  Sanitary  Dust  Removal 
Company,  of  San  Francisco,  and,  later,  was  taken  over  by  the 
American  Rotary  Valve  Company,  of  Chicago,  which  is  now 


HISTORY   OF  MECHANICAL   CLEANING  19 

marketing  same.  It  eliminates  the  manual  handling  of  the  dust 
at  any  stage  of  its  removal,  a  feature  which  is  made  much  of 
by  its  manufacturers,  but  one  which  is  likely  to  cause  some 
trouble  for  the  sewerage  system  if  care  is  not  exercised. 

Machines  Using  Root  Blowers  as  Vacuum  Producers. — 
The  use  of  a  Root  type  of  rotary  pump  as  a  vacuum  producer 
was  first  undertaken  by  the  Foster  and  Glidden  Engineering 
Company,  of  Buffalo,  which  marketed  the  Acme  system  about 
1907,  the  same  company  having  previously  built  a  simliar  sys- 
tem for  the  removal  of  grain  from  steam  barges.  The  other 
features  of  this  system  did  not  differ  materially  from  those 
already  on  the  market. 

Being  familiar  with  the  various  uses  to  which  this  type  of 
vacuum  pump  had  been  adapted,  the  principal  one  being  the 
operation  of  pneumatic  tube  systems,  the  author  suggested  the 
use  of  this  type  of  vacuum  producer  about  two  years  previous 
to  its  introduction  and  was  advised  by  one  manufacturer  that 
such  a  type  of  pump  was  not  suitable  for  vacuum  cleaning. 
The  fallacy  of  this  statement  will  be  brought  out  in  detail 
in  a  later  chapter. 

The  type  of  vacuum  producer  just  described  has  been  adopted 
in  many  makes  of  vacuum  cleaners,  including  the  Hope,  Con- 
nellsville,  Arco,  and,  lately,  in  the  American  Rotary  Valve 
Company's  smaller  systems. 

During  the  past  four  years  a  score  or  more  of  new  stationary 
vacuum  cleaning  systems  have  been  introduced,  among  which 
are  the  Palm,  a  modification  of  the  Dunn-Locke  system;  the 
Tuec,  a  turbine  cleaner;  the  Water  Witch,  which  uses  a  water- 
operated  turbine  as  a  vacuum  producer,  and  the  Hydraulic, 
with  water-operated  ejector.  At  the  same  time  a  hundred  or 
more  portable  vacuum  cleaners  have  been  marketed.  These 
are  of  almost  every  conceivable  type  and  form  and  are  operated 
by  hand,  electricity,  and  water  power.  Among  them  will  be 
found  machines  which  are  good,  bad  and  indifferent,  the  effi- 
ciency and  economy  of  which  will  be  discussed  in  a  later  chapter. 

This  nearly  universal  invasion  of  the  vacuum  cleaner  field 
by  anybody  and  everybody  looking  for  a  good  selling  article, 
establishes  the  fact  that  the  vacuum  cleaner  is  not  a  fad  or 
fancy,  but  has  become  almost  a  household  necessity  and  has  led 


20  VACUUM    CLEANING    SYSTEMS 

large  corporations  to  take  it  up  as  a  branch  of  their  business. 
First,  the  Sanitary  Devices  Manufacturing  Company  and  the 
Vacuum  Cleaner  Company,  the  pioneers  in  the  field,  after  a 
legal  battle  of  years,  consolidated  with  a  view  of  driving  their 
competitors  from  the  field  as  infringers  of  the  patents  con- 
trolled by  the  two  organizations.  The  result  of  this  was  the 
licensing  of  other  companies.  In  an  attempt  to  control  the  sale 
of  their  type  of  apparatus  notice  was  served  on  all  users  of 
other  types  of  vacuum  cleaners  that  they  were  liable  to  prose- 
cution for  using  infringing  apparatus. 

Later,  the  McCrum-Howell  Company,  a  manufacturer  of 
heating  boilers  and  radiators,  secured  control  of  the  products  of 
the  American  Air  Cleaning  Company  and  the  Vacuum  Clean- 
er Company  and  sold  these  machines  to  the  trade  for  installa- 
tion by  the  plumbers  and  steam  fitters.  The  McCrum-Howell 
Company  has  been  succeeded  by  the  Richmond  Radiator  Com- 
pany, which  is  handling  these  vacuum  cleaning  machines. 

Shortly  afterwards,  the  United  States  Radiator  Corporation 
secured  control  of  the  Invincible  and  the  Connellsville  systems, 
and,  lastly,  the  American  Radiator  Company  secured  the  Wand 
system. 

Thus  we  see  that  vacuum  cleaning  seems  to  be  virtually  in 
the  control  of  the  manufacturers  of  heating  apparatus,  who 
are  also  among  the  largest  corporations  in  this  country  and 
well  able  to  control  the  future  of  this  business  to  their  liking. 

As  to  the  future  of  vacuum  cleaning  the  author  considers  that 
it  is  at  present,  like  the  automobile,  at  the  height  of  its  career, 
and  also,  like  the  automobile,  that  it  is  a  useful  appliance  to 
mankind  and  that  it  has  its  proper  place  as  a  part  of  the 
mechanical  equipment  of  our  modern  buildings. 

As  to  the  type  of  vacuum  cleaner  of  the  future,  the  author 
believes  that  these  appliances  will  become  standardized,  just 
as  all  other  useful  appliances  have  been,  and  that  the  form 
that  it  will  then  take  will  be  a  survival  of  the  fittest.  What 
that  form  may  resemble  the  reader  may  more  readily  judge 
when  he  has  completed  the  reading  of  this  book. 


CHAPTER  II. 

REQUIREMENTS  OF  AN   IDEAL  VACUUM   CLEANING  SYSTEM. 

Before  a  comparison  of  the  relative  merits  of  any  line  of 
appliances,  used  for  any  one  purpose,  can  be  intelligently  made, 
one  must  have  either  some  form  of  that  apparatus  which  we 
consider  as  a  standard  for  comparison  that  we  may  rate  all 
others  as  inferior  or  superior  thereto,  or  else  an  ideal  of  a 
perfect  system  must  be  assumed,  and  the  measures  with  which 
each  of  the  various  appliances  approaches  the  requirements  of 
the  ideal  will  establish  their  relative  merits. 

The  author  has  elected  to  use  the  latter  method  in  comparing 
the  various  systems  of  vacuum  cleaning,  and  it  is  necessary, 
therefore,  to  first  determine  what  are  the  requirements  we  shall 
impose  on  the  ideal  system. 

An  ideal  vacuum  cleaning  system  would  be  one  which,  when 
installed  in  any  building,  will  displace  all  appliances  used  for 
dry  cleaning  in  the  semi-annual  renovating  or  house  cleaning, 
the  weekly  cleaning  or  Friday  sweeping  and  the  daily  supple- 
mental cleaning.  If  our  system  be  truly  an  ideal  one,  the 
premises  should  never  become  so  dirty  as  to  require  any  semi- 
annual cleaning  at  all,  and,  if  the  daily  cleaning  be  anyway 
thorough,  there  need  be  no  weekly  cleaning.  This  latter  con- 
dition may  be  governed  by  the  will  of  the  housekeeper  or 
janitor. 

The  compressed  air  cleaners  first  introduced  were  intended 
for  use  only  at  the  semi-annual  cleaning  and  they  were  in 
reality  carpet  renovators,  which  were  assumed  as  imparting  to 
the  carpets  all  the  beneficial  results  that  could  be  obtained  by 
taking  them  up  and  sending  them  to  a  carpet-cleaning  estab- 
lishment, with  the  advantage  over  this  latter  method,  that  the 
labor  of  removal  and  replacement  of  the  carpets  was  rendered 
unnecessary,  but  with  the  disadvantage  that  all  the  germ-laden 

21 


22  VACUUM    CLEANING    SYSTEMS 

air,  used  as  a  means  of  cleaning  the  carpets,  was  blown  back 
into  the  apartment,  leaving  the  germs  in  their  former  abode. 

This  disadvantage,  however,  is  partly  offset  by  the  fact 
that  while  the  majority  of  the  grms  in  one's  own  carpet  are 
blown  out  at  the  carpet  cleaners,  a  mixed  company  of  germs 
from  your  neighbors'  and  others'  carpets,  which  may  be  in  the 
tumbling  barrel  at  the  same  time  with  your  own,  are  returned 
to  you  with  your  carpet. 

Neither  of  these  conditions  is  ideal  and  we  will  expect  our 
ideal  cleaner  to  completely  remove  from  the  premises,  not  only 
the  dust  and  dirt,  but  also  the  germ-laden  air  which  is  used  as 
a  means  of  conveying  this  dirt. 

For  replacing  the  weekly  and  the  daily  cleaning,  these  earlier 
renovators  were  not  suitable,  as  in  order  to  use  same  the  fur- 
niture must  all  be  removed  from  the  apartment. 

To  accomplish  this  daily  and  weekly  cleaning,  the  ideal 
vacuum  cleaner  must  replace  the  broom  and  dust  pan,  and 
their  inseparable  companion,  the  duster,  and  must  also  super- 
sede that  time-honored  mechanical  cleaner,  the  carpet  sweeper. 

The  reader  will  doubtless  consider  that  in  making  this  state- 
ment the  author  is  asking  the  vacuum  cleaner  to  perform  much 
more  than  it  is  usually  called  on  to  do.  However,  we  are  now 
discussing  an  ideal  system,  and  the  above  requirements  are  not 
absolutely  beyond  what  can  be  accomplished  by  some  of  the 
cleaning  systems  now  on  the  market. 

To  accomplish  this  requirement  the  ideal  cleaner  must  pick 
up  everything  likely  to  be  found  on  the  floor  which  cannot 
be  readily  picked  up  by  hand.  The  character  of  this  material 
will  vary  greatly  according  to  the  uses  of  'the  apartment 
cleaned.  In  residences  and  offices,  where  carpets  or  rugs  are  in 
use,  cigar  stumps  and  matches  are  usually  deposited  in  cuspidors 
and  small  pieces  of  paper  in  waste  baskets,  consequently  there 
should  be  nothing  but  dust  to  be  removed  from  a  residence  and, 
perhaps,  mud  and  sand  from  the  shoes  of  the  many  visitors, 
in  addition  to  the  dust  in  an  office. 

However,  there  are  special  conditions  likely  to  be  met  in  many 
cases ;  sewing  rooms  will  be  littered  with  basting  threads  and 
scraps  of  cloth;  department  stores,  with  a  great  quantity  of 
pins;  banking  rooms  with  bands  and  large-sized  bank  pins;  all 


REQUIREMENTS  OF  AN  IDEAL  SYSTEM          23 

of  which  increase  the  requirements  of  the  ideal  system.  A 
cleaner  which  is  perfectly  adapted  to  one  sort  of  apartment 
will  be  entirely  unsuited  for  another,  and  the  ideal  cleaner 
will  be  one  which  can  be  readily  adapted  to  all  conditions  likely 
to  be  met  in  the  building  in  which  it  is  installed. 

The  ideal  cleaner  must  be  able  to  accomplish  the  above  stated 
requirements  without  the  necessity  of  moving  heavy  pieces  of 
furniture  out  of  or  about  the  apartment;  that  is,  it  must  be 
capable  of  being  efficiently  operated  under  beds,  tables  and 
chairs,  around  the  legs  of  other  heavy  furniture,  behind  book- 
cases, pianos,  cabinets,  etc.,  over  curtains,  draperies  and  hang- 
ings, over  walls,  behind  pictures  and  over  mouldings  and  carved 
ornaments,  all  without  injury  to  any  of  the  furniture  or  fittings 
of  the  apartment,  and  with  the  least  expenditure  of  energy  by 
the  operator. 

These  conditions  should  be  met  with  the  fewest  possible  num- 
ber of  cleaning  appliances,  none  of  which  should  be  provided 
with  small  attachments  liable  to  be  lost  or  misplaced,  and  all 
parts  of  the  system,  which  must  necessarily  be  moved  about, 
either  before,  after  or  during  the  cleaning  operation,  should  be 
of  minimum  weight  and  bulk,  but  of  rugged  and  lasting  con- 
struction. 

The  ideal  vacuum  cleaner  should  be  of  such  proportions  and 
provided  with  ample  motive  power  to  clean  rapidly  and 
effectively. 

For  use  in  an  office  building  the  cleaner  should  be  able  to 
thoroughly  clean  an  average-sized  office,  including  floor,  walls, 
furniture  and  fittings  in  from  10  to  15  minutes,  and  for  resi- 
dence work,  should  be  of  sufficient  capacity  to  clean  an  apart- 
ment, including  floor,  walls,  curtains,  draperies,  pictures  and 
furniture  in  not  exceeding  30  minutes. 

The  ideal  system  should  be  so  arranged  that  any  apart- 
ment in  the  building  can  be  cleaned  with  the  least  possible 
disturbance  and  without  affecting  the  use  of  any  other  apart^ 
ment,  excepting  perhaps,  the  corridors  or  hallways. 

In  large  offices,  drafting  rooms  and  similar  apartments,  it 
may  become  necessary  to  clean  same  while  they  are  occupied; 
therefore,  our  ideal  system  must  be  practically'  noiseless  in 
operation  and  must  offer  the  least  possible  obstruction  to  the 
proper  use  of  the  room  by  its  regular  occupants. 


24  'VACUUM  CLEANING  SYSTEMS 

Necessity  and  Proper  Location  of  Stationary  Parts. — To  be 
of  sufficient  power  to  do  rapid  cleaning  and  in  order  to  remove 
from  the  building  all  dust  and  germ-laden  air,  the  cleaning 
system  must  necessarily  contain  some  stationary  parts.  The 
motive  power  can  generally  be  confined  to  these  stationary 
parts,  and  must,  in  such  cases,  be  located  within  the  building 
to  be  cleaned.  Therefore,  it  should  operate  with  the  minimum 
of  noise  and  vibration. 

Machines  located  in  office  or  other  large  buildings,  containing 
elevators  or  other  complicated  apparatus  requiring  skilled  at- 
tendance, which  are  provided  with  complicated  control  and 
with  other  attachments,  are  not  objectionable,  and  in  such 
cases  simplicity  should  give  way  to  efficiency,  but  unnecessary 
complications  should  be  avoided. 

In  residences  and  other  small  buildings,  where  the  vacuum 
cleaner  is  likely  to  be  the  only  machinery  installed,  the  sys- 
tem must  be  one  which  requires  the  minimum  attention  and 
must  be  capable  of  being  started  and  stopped  by  any  person  of 
average  ability,  without  the  necessity  of  going  to  the  point 
where  the  machine  is  located. 

The  power  consumption  of  the  ideal  system  should  be  a 
minimum  to  accomplish  satisfactory  results  and  should  be,  as 
nearly  as  possible,  directly  proportioned  to  the  amount  of  clean- 
ing being  done.  This  requirement  is  most  important  in  hotels, 
where  some  cleaning  is  likely  to  be  done  at  all  hours,  day  and 
night.  In  other  words,  vacuum  must  be  "on  tap"  and  as 
readily  attainable  at  any  point  in  the  building  as  your  water 
or  electric  light.  In  office  buildings,  where  a  schedule  of  clean- 
ing hours  is  fixed,  and  in  residences  where  cleaning  hours  are 
few  and  the  capacity  of  the  plant  is  rarely  more  than  could  be 
attended  to  by  one  operator,  this  requirement  is  not  of  as 
great  importance. 

Lastly,  our  ideal  system,  from  the  standpoint  of  the  pur- 
chaser, must  be  of  such  rugged  construction,  as  will  enable  it 
to  operate  efficiently  for,  at  least,  ten  years  and  its  mechanical 
details  such  that  it  will  operate  continuously,  without  expert 
attention,  and  that  the  annual  expense  for  repairs  during  the 
life  of  the  machine  will  not  exceed  5%  of  the  first  cost  of  the 
system. 


CHAPTER  III. 
THE  CARPET  RENOVATOR. 

In  undertaking  the  comparison  of  a  number  of  different 
makes  of  any  appliance,  in  order  to  determine  the  good  and 
bad  points  in  each,  where  the  apparatus  is  composed  of  a 
number  of  separate  and  distinct  parts,  each  having  its  proper 
function,  which  they  must  perform  in  order  to  make  the  whole 
apparatus  effective,  as  in  a  vacuum  cleaning  system,  it  becomes 
necessary  to  isolate  temporarily  each  part  and  consider  its 
action,  first,  as  a  unit  working  under  the  most  favorable  con- 
ditions, and,  second,  as  a  component  part  of  the  whole  ap- 
paratus in  order  to  determine  where  the  weak  points  in  any 
system  occur  and  what  modifications  are  necessary  in  the  vari- 
ous parts  of  the  apparatus  to  make  some  vital  part  of  the 
whole  more  effective.  It  is  further  necessary  to  determine 
what  are  the  vital  parts  of  the  system  in  order  that  the  other 
parts  may  be  accommodated  to  the  effective  action  of  that  part. 

Four  Important  Parts  of  Vacuum  Cleaning  System. — In 
analyzing  a  vacuum  cleaning  system  it  naturally  divides  itself 
into  four  parts,  viz. :  the  cleaning  tool  or  renovator,  the  air- 
conveying  system  or  hose  and  pipe  lines,  the  separators  or 
other  means  of  disposal  of  the  material  picked  up,  and  the 
vacuum  producer. 

The  author  considers  that  the  renovator  is  the  most  impor- 
tant part  of  the  system  and  that  the  other  parts  should  be  made 
of  such  proportions  and  with  such  physical  characteristics  as 
will  produce  the  proper  conditions  at  the  renovator  to  permit 
it  to  perform  its  functions  in  the  most  effective  manner. 

As  the  vacuum  cleaning  system  must  be  capable  of  cleaning 
surfaces  of  a  widely  variable  character  many  forms  of  reno- 
vators are  necessary.  Of  the  various  surfaces  cleaned  the 
author  considers  that  carpets  and  rugs  comprise  the  most  im- 

25 


26  VACUUM    CLEANING    SYSTEMS 

portant,  as  well  as  the  most  difficult  to  clean  effectively,   so 
that  the  carpet  renovator  will  be  considered  first. 

The  Straight  Vacuum  Tool. — Various  forms  of  carpet  ren- 
ovators have  been  and  are  in  use  by  manufacturers  of  vacuum 
cleaning  systems.  The  first  type  of  renovator  to  be  considered 
is  that  having  a  cleaning  slot  not  over  12  in.  long,  with  its 
edges  parellel  throughout  its  length,  and  not  over  ^  in.  wide, 
with  a  face  in  contact  with  the  carpet  not  over  ^  in.  wide  on 
each  side  of  the  slot.  This  form  of  renovator  is  illustrated  in 
Fig.  11  and  is  designated  by  the  writer  as  Type  A.  The  first 


FIG.  12.   TYPE  B,  WITH  WIDE 
FIG.  11.   TYPE  A,  THE  STRAIGHT          SLOT  AND  WIDE  BEARING 
VACUUM  TOOL.  SURFACE. 


of  these  renovators  was  introduced  by  Mr.  Kenney  and,  as 
finally  adopted  by  him,  was  12^  in.  long,  with  %-in.  face  and 
with  a  cleaning  slot  11^2  in.  long  and  5/32  in.  wide.  This  form 
of  cleaner  was  termed  the  "straight  vacuum  tool"  and  is  used 
today  by  many  manufacturers.  Slight  modifications  in  its  form 
and  dimensions  were  made  in  some  cases,  as  in  the  one  manu- 
factured by  the  American  Air  Cleaning  Company.  In  the  one 
used  in  all  tests  by  the  writer  on  type  A  renovators,  the  slot 
was  reduced  to  10  in.  long  and  %  in.  wide  and  the  face  of  the 
renovator  was  slightly  rounded  at  the  outer  edges,  leaving  very 
little  surface  in  contact  with  the  carpet.  .: 

A  renovator  of  this  type  is  easily  operated  over  any  carpet 
even  when  a  considerable  degree  of  vacuum  exists  within  the 
renovator  itself.  It  has  met  with  favor  when  used  with  the 
piston  type  of  vacuum  pump  without  vacuum  control,  as  was 
the  case  with  the  earlier  systems.  However,  when  a  very  high 


THE  CARPET  RENOVATOR*  27 

degree  of  vacuum  occurs  within  the  renovator  it  has  a  tendency 
to  pull  the  nap  from  the  pile  of  the  carpet. 

Soon  after  the  introduction  of  this  form  of  renovator,  some 
users  of  same,  particularly  in  San  Francisco,  complained  that 
while  the  renovator  effectively  removed  the  dust  from  carpets 
it  failed  to  pick  up  matches  and  other  small  articles  and  pre- 
liminary or  subsequent  cleaning  was  necessary  in  order  to 
remove  such  litter. 

To  overcome  this  difficulty  Mr.  Kenney  increased  the  width 
of  the  cleaning  slot  to  nearly  y^  in.,  with  the  result  that  when 
a  high  degree  of  vacuum  existed  within  the  renovator,  which 
often  occurred  where  no  vacuum  control  was  used,  it  stuck  to 
the  carpet,  rendering  its  operation  difficult  and,  at  the  same 
time,  doing  great  damage  to  the  carpet.  Hence,  its  use  with  the 
piston  type  of  vacuum  pumps  was  abandoned. 

Mr.  Kenney  then  modified  this  wide  slot  renovator  by  making 
the  face  of  same  much  wider,  thus  having  more  surface  in 
contact  with  the  carpet  on  each  side  of  the  slot,  preventing  the 
renovator  from  sinking  into  the  nap  of  the  carpet.  This  type 
of  renovator  is  illustrated  in  Fig.  12  and  has  been  designated 
as  Type  B.  While  not  as  destructive  to  the  carpets,  when  a 
high  degree  of  vacuum  existed  under  the  same,  it  still  pushed 
hard  and  was  not  as  rapid  a  cleaner  as  the  narrow-lipped  Type 
A  renovator. 

Renovator  with  Auxiliary  Slot  Open  to  Atmosphere.— 
The  renovator  introduced  by  the  Sanitary  Devices  Manufac- 
turing Company  differed  widely  from  the  former  types  in 
that  it  was  provided  with  an  auxiliary  slot,  open  to  the  atmos- 
phere through  the  top  of  the  renovator,  which  communicated 
with  the  slot  open  to  the  vacuum  by  a  space  of  1/32-in.  under 
the  partition  separating  the  slots.  The  cleaning  slot  was  made 
5/16-in.  wide  and  the  face  of  the  renovator  was  made  2-in.  wide, 
which  gave  a  contact  of  13/32-in.  in  front  of  the  inrush  slot 
and  21/32-in.  in  the  rear  of  the  cleaning  slot.  This  form  of 
renovator  is  illustrated  in  Fig.  13  and  is  designated  as  Type  C. 

The  auxiliary  slot  or  vacuum  breaker  permitted  air  to  enter 
the  cleaning  slot  even  when  the  renovator  was  placed  on  a 
surface  plate,  and,  owing  to  this  feature,  a  high  degree  of 
vacuum  never  existed  within  the  renovator.  It  was  always 


28 


VACUUM    CLEANING    SYSTEMS 


easy  to  operate  and  did  not  damage  the  carpet.  Owing  to  the 
wide  slot,  articles  of  considerable  size  could  be  picked  up,  and 
there  was  always  an  abundance  of  air  passing  through  the 
renovator  to  produce  a  velocity  in  the  hose  and  pipe  lines 
sufficient  to  carry  any  heavy  articles  picked  up. 

The  vacuum  producer,  control  apparatus  and  the  proportions 
of  the  hose  and  piping  used  at  that  time  made  the  degree  of 
vacuum  in  the  renovator  a  function  of  the  quantity  of  air 
passing,  with  wide  limits  of  variation  under  existing  conditions, 
and  this  form  of  renovator  is  practically  the  only  one  which 
will  do  effective  cleaning,  including  the  picking  up  of  litter, 
without  undue  wear  on  carpets,  when  used  with  a  system 
having  the  above-stated  characteristics.  This  renovator,  how- 
ever is  not  without  its  faults.  Owing  to  the  wide  surface  in 
contact  with  the  carpet,  a  considerable  degree  of  vacuum  is 
necessary  in  order  that  any  air  shall  enter  the  renovator  under 


FIG.   13.      TYPE   C,   WITH   AUX- 
ILIARY SLOT,  OPEN  TO 
ATMOSPHERE. 


FIG.  14.      TYPE  D,  WITH  TWO 
CLEANING  SLOTS. 


the  faces  of  same  and,  as  the  air  entering  the  inrush  slot  pre- 
vents the  formation  of  such  vacuum  within  the  renovator,  very 
little  air  enters  the  renovator  between  itsi  face  and  the  carpet. 
When  the  renovator  is  operated  on  a  carpet  having  a  glue-sized 
back,  no  air  enters  through  the  carpet,  therefore  all  air  entering 
the  renovator  must  come  through  the  inrush  slot  and  under  the 
partition  separating  same  from  the  cleaning  slot.  Under  these 
conditions  only  one  side  of  the  vacuum  slot  is  effective  and  this 
effective  side  is  raised  above  the  surface  of  the  carpet. 

When  operated  on  an  ingrain  or  other  loose-fabric  carpet, 
much  air  enters  through  the  fabric  of  the  carpet,  due  to  the 


THE  CARPET  RENOVATOR  29 

wide  cleaning  and  inrush  slots,  in  addition  to  the  quantity  of 
air  entering  through  the  inrush  slot,  making  this  renovator, 
when  operating  under  these  conditions,  use  an  unnecessary 
amount  of  air.  Apparently,  this  renovator  has  been  designed 
to  prevent  the  formation  of  any  great  degree  of  vacuum  under 
same  and  such  a  design  has  resulted  in  a  greater  volume  of 
air  at  a  lower  vacuum  passing  through  than  through  renovators 
of  other  types. 

.  This  property  of  the  renovator  raises  the  question  whether 
the  quantity  of  air  or  the  degree  of  vacuum  in  the  renovator 
is  most  essential  for  the  removal  of  dirt  from  carpets.  Tests 
made  by  Mr.  S.  A.  Reeve,  consulting  engineer  for  the  Vacuum 
Cleaner  Company,  with  this  type  of  renovator,  with  the  in- 
rush open  and  repeated  with  the  inrush  closed,  disclose  the 
fact  that  it  does  more  effective  cleaning  with  its  inrush  closed, 
while  the  volume  of  <air  passing  is  considerably  less  with  the 
inrush  closed.  The  degree  of  vacuum  was  greater,  which  tends 
to  indicate  that  the  vacuum  within  the  renovator  is  the  most 
important  factor. 

An  extract  from  the  affidavits  of  Mr.  Reeve  in  one  of  the 
numerous  patent  suits  will  show  his  explanation  of  this  phe- 
nomenon: "If  we  examine  more  closely  into  the  actual  process 
whereby  such  a  sweeper  succeeds  in  extracting  dust  from  car- 
pets, etc.,  it  will  appear  that  the  actual  cleaning  is  effected 
at  the  periphery  of  the  slot  in  the  lower  surface  of  the  sweeper. 
It  is  accomplished  chiefly  by  the  development  of  local  changes 
of  air  pressure  at  the  lips  defining  this  slot,  incidentally  to  the 
movement  of  the  tool  over  the  carpet.  These  changes  cause 
the  air  occupying  the  interstices  between  the  dust  particles  to 
expand  suddenly,  thus  'raising  the  dust/  To  a  lesser  degree, 
the  scouring  is  effected  by  highly  localized  air  currents  of  con- 
siderable velocity,  engendered  where  the  tool  comes  in  contact 
with  the  carpet.  These  air  currents  pick  up  the  dust  which 
has  already  been  expanded  or  raised  by  pressure  change.  They 
will  be  of  higher  velocity,  and  therefore  more  effective,  the 
better  the  contact  of  the  tool  with  the  carpet.  The  same  is 
true  of  the  pressure  changes. 

"All  this  action  depends  for  its  intensity,  speed  and  effec- 
tiveness, not  on  the  vacuum  existing  at  the  pump  or  in  the 


30  VACUUM    CLEANING    SYSTEMS 

separators,  but  upon  the  vacuum  prevailing  within  the  sweeper 
head  itself." 

Renovator  with  Two  Cleaning  Slots. —  Another  form  of 
renovator  was  introduced  by  the  Blaisdell  Machinery  Company 
which  contained  two  cleaning  slots  each  3/16-in.  wide  and  12-in. 
long,  separated  by  a  partition  ^4 -in.  wide  in  contact  with  the 
surface  of  the  carpet,  as  indicated  in  Fig.  14  (Type  D).  While 
this  form  of  renovator  has  a  greater  area  of  cleaning  slot  than 
Type  A,  its  individual  cleaning  slots  are  no  wider;  therefore, 
it  cannot  pick  up  anything  larger  than  can  be  picked  up  by 
Type  A.  As  no  air  can  enter  under  the  partition  it  can 
do  no  more  effective  work  as  a  dust  remover  when  operated  on 
a  carpet  with  a  glue-sized  back  and  its  only  advantage  over  a 
cleaner  of  Type  A  is  that  when  operated  on  a  loose-fabric  carpet 
more  air  can  pass  through  the  fabric  into  the  cleaning  slot, 
thus  giving  a  greater  variation  in  the  quantity  of  air  exhausted 
when  operated  on  carpets  of  different  texture,  a  condition  which 
is  undesirable  when  used  with  a  system  having  characteristics 
previously  described. 

Tests  of  this  type  of  renovator,  made  by  Mr.  Reeve,  are  given 
later  in  this  chapter. 

Renovator  with  Inrush  Slots  on  Each  Side. — Another  form 
of  renovator,  introduced  by  Mr.  Moorhead,  is  illustrated  in 
Fig.  15  (Type  E).  This  is  a  modification  of  Type  A  in  that 
an  inrush  slot  is  provided  on  each  side  of  the  vacuum  slot, 
these  inrushes  being  hinged  members  which  form  the  sides 
of  the  cleaning  slot.  This  cleaner  has  the  advantage  over  Type 
C  renovator  in  that  it  can  take  air  from  either  side,  but  in 
action  it  takes  air  from  but  one  side  at  any  time.  Its  inrush 
will  not  become  entirely  clogged,  but  its  mechanically-moving 
parts  in  contact  with  the  dust  and  lint  picked  up  will  easily 
become  inoperative  and  are  as  like  as  not  to  become  caught 
wide  open  when  the  air  entering  the  cleaner  will  not  come  into 
intimate  contact  wtih  the  carpet.  In  that  event,  its  cleaning 
efficiency  will  be  greatly  reduced.  The  author  has  not  had  an 
opportunity  to  make  any  comparative  tests  of  this  form  of 
renovator. 

When  Mr.  Spencer  introduced  the  centrifugal  fan  as  a 
vacuum  producer,  he  also  brought  out  a  series  of  carpet  reno- 


THE  CARPET  RENOVATOR 


31 


vators  of  various  forms  and  sizes.  One  had  a  cleaning  slot 
24-in.  wide  and  10-in.  long,  another  a  slot  15-in.  long,  %-in. 
wide  at  its  end,  increasing  to  24 -in.  at  the  center.  Another 
had  a  slot  20-in.  long  and  •Hj-in.  wide,  and  finally  he  adopted  a 
tool  with  a  cleaning  slot  15-in.  long  and  ^2 -in.  wide  throughout 
its  length.  This  is  merely  the  re-entrance  into  the  field  of  the 
wide-slot  tool  first  used  by  Mr.  Kenney  and  its  successful  opera- 
tion depends  on  its  use  with  a  vacuum  producer  of  such  char- 
acteristics and  a  hose  and  pipe  line  of  such  proportions  that 
practically  a  constant  vacuum  is  maintained  within  the  reno- 
vator, regardless  of  the  quantity  of  air  passing  through  the 
tool.  The  latest  form  of  this  renovator,  as  used  by  Mr.  Spencer, 
is  illustrated  in  Fig.  16.  At  the  time  that  the  writer  made  tests 
on  renovators  of  this  make,  the  majority  of  the  tests  were  made 
with  a  renovator  having  a  cleaning  slot  10-in.  long  and  ^4 -in. 


FIG.   15.      TYPE    E,    WITH   INRUSH 

SLOT  ON   EACH   SIDE    OP 

VACUUM  SLOT. 


FIG.  16.   TYPE  F,  AN  EXAG- 
GERATED FORM  OF 
TYPE  B. 


wide.     This   renovator    is   designated   as   Type   F,   while   the 
15-in.  x  X'in-  to  24-in-  sl°t  is  designated  as  Type  F1. 

About  seven  years  ago  the  Supervising  Architect  of  the 
United  States  Treasury  Department  gave  consideration  to  the 
use  of  a  carpet  cleaning  test  to  determine  the  acceptability  of 
any  vacuum  cleaning  system  which  might  be  installed  in  any  of 
the  buildings  under  his  control.  The  author  was  instructed 
to  make  a  series  of  tests  of  carpet  renovators,  with  a  view  of 
determining:  (1)  the  feasibility  of  using  a  carpet  cleaning  test 
to  determine  the  merits  of  a  vacuum  cleaning  system;  (2)  to 


32  VACUUM    CLEANING    SYSTEMS 

fix  the  requirements  to  be  incorporated  in  a  specification  where 
the  acceptance  of  the  system  was  dependent  on  a  satisfactory 
carpet  cleaning  test,  to  be  made  at  the  building  after  the  com- 
pletion of  the  installation;  (3)  to  determine  what  requirements, 
other  than  a  cleaning  test,  would  be  necessary  to  obtain  a 
first-class  cleaning  system. 

The  record  of  many  such  tests  was  shown  to  the  author,  shortly 
before  he  began  making  tests.  These  purported  to  have  been 
made  by  Prof.  Miller  at  the  Massachusetts  Institute  of  Tech- 
nology, with  a  pump  furnished  by  the  Sanitary  Devices  Manu- 
facturing Company,  in  which  the  efficiency  of  the  inrush  type 
of  renovator  (Type  C)  and  the  straight  vacuum  renovator 
(Type  A)  was  compared.  The  results  of  these  tests,  as  given 
in  a  brief  resume,  which  was  distributed  by  the  Sanitary 
Devices  Manufacturing  Co.,  indicated  that  the  Type  C  reno- 
vator was  the  more  rapid  and  efficient  cleaner. 

The  author  learned  that  these  tests  were  made  by  the  under- 
graduate students  as  a  part  of  the  regular  laboratory  work, 
and  that  later  a  series  of  tests  was  made  as  the  basis  of  a 
thesis  by  Messrs.  Paterson  and  Phelps  in  1906,  using  the  above- 
described  apparatus.  The  following  year  another  series  of  tests 
was  made  by  Mr.  Stewart  R.  Miller,  as  the  basis  of  an  under- 
graduate thesis,  in  which  the  efficiencies  of  the  piston  pump  and 
inrush  sweeper  of  the  Sanitary  Devices  Manufacturing  Co. 
were  compared  with  those  of  the  steam  aspirator  and  straight 
vacuum  renovator  of  the  American  Air  Cleaner  Company.  A 
copy  of  this  thesis  was  furnished  the  author  by  the  Sanitary 
Devices  Manufacturing  Company  shortly  after  the  completion 
of  the  tests  made  by  the  author. 

The  relative  efficiency  of  the  two  types  of  renovators  reported 
by  these  tests  differed  widely  in  each  case,  an  occurrence 
which  is  liable  to  happen  where  undergraduate  students  are 
engaged  in  such  work.  They  were,  therefore,  considered  as  of 
doubtful  reliability. 

The  author  could  find  no  record  of  any  tests  made  by  anyone 
of  longer  experience  and,  indeed,  these  were  the  only  tests  of 
which  he  could  find  any  record. 

As  the  author  desired  to  specify  a  cleaning  test  which  could 
be  readily  repeated  at  the  building  in  which  the  cleaning  sys- 


THE  CARPET  RENOVATOR '  33 

tern  was  installed,  which  building  was  likely  to  be  located  in 
any  part  of  the  United  States,  no  exhaustive  laboratory  methods 
were  desired  or  attempted.  As  the  building  was  likely  to  be 
located  in  a  city  where  no  other  vacuum  cleaning  systems  were 
then  installed  and  in  a  new  building  in  which  no  dirty  carpets 
were  available,  and  as  it  was  not  desirable  to  have  the  con- 
tractor furnish  the  material  for  the  test,  it  was  considered  nec- 
essary to  use  some  material  in  soiling  carpets  which  would  be 
readily  obtainable  anywhere,  which  could  be  readily  brought  to 
a  standard,  and  which,  when  worked  into  the  carpets  in  a 
reasonable  length  of  time,  would  be  as  difficult  to  remove  as 
the  dirt  found  in  the  average  dirty  carpet. 

Tests  on  Dirty  Carpets. — As  no  tests  of  cleaning  an  actually 
dirty  carpet  were  on  record,  quicksand  having  been  used  in  the 
Institute  of  Technology  tests,  it  was  necessary  to  first  clean 
some  carpets  that  had  been  soiled  in  actual  daily  service  in 
order  to  obtain  a  standard  with  which  to  compare  the  results 
in  removing  various  substances,  which  it  was  intended  to  try 
as  a  substitute  for  dirt,  A  carpet  which  had  been  in  actual  use 
for  a  number  of  years  on  the  floors  of  the  old  United  States 
Mint  building,  in  Philadelphia,  and  receiving  the  ordinary 
amount  of  cleaning,  was  procured.  This  was  a  Brussels  car- 
pet with,  a  glue-sized  back,  containing  about  20  sq.  yds.  It- 
was  divided  into  three  approximately  equal  parts. 

An  indicator  was  attached  to  the  vacuum  pump  for  taking 
air  measurements,  and  it  was  found  that  there  was  consider- 
able leakage  of  air  into  the  system  through  the  connections  to 
the  separators  and  at  other  points,  therefore  the  pump  was 
operated  with  22  in.  of  vacuum  in  the  separator  and  a  card  taken 
with  all  outlets  closed  and  the  amount  of  leakage  noted.  Dur- 
ing the  tests  this  degree  of  vacuum  was  always  maintained  in 
the  separators  and  pipe  lines  and  the  vacuum  in  the  renovator 
was  varied  throughout  the  tests  by  throttling  the  hose  cock. 
This  manner  of  making  tests  gave  a  practically  constant  leak- 
age which  was  deducted  from  the  quantities  shown  by  the 
indicator  cards  taken  with  the  renovators  in  operation. 

As  the  writer  had  already  made  many  tests  of  the  efficiency 
of  various  types  of  vacuum  pumps  as  air  movers  under  various 
degrees  of  vacuum,  and  as  the  capacity  of  the  pump  available 


34 


VACUUM    CLEANING    SYSTEMS 


was  far  in  excess  of  that  required  to  operate  one  renovator, 
no  attempt  to  obtain  the  efficiency  of  the  plant  as  a  unit  was 
made.  Instead,  the  vacuum  at  the  hose  cock  was  adjusted  until 
the  degree  obtained  was  what  the  writer  had  found  to  be  within 
the  limit  obtained  in  practice.  The  resulting  vacuum  at  the 
renovator  was  then  noted. 

Each  piece  of  carpet  was  cleaned  during  six  periods  of  one 
minute  each,  using  a  different  vacuum  at  the  tool  for  each 
piece  of  carpet.  The  carpets  were  weighed  at  the  beginning 
of  the  test  and  after  each  one-minute  period.  At  the  conclusion 
of  these  tests  each  carpet  was  cleaned  until  no  change  of  weight 
occurred  after  two  minutes'  cleaning.  They  were  then  con- 
sidered as  being  100%  clean  and  this  standard  was  made  a 
basis  for  computing  the  percentage  of  dirt  removal.  A  reno- 
vator of  Type  C  was  used  in  these  tests. 

Shortly  afterward  a  similar  test  was  made  on  a  dirty  carpet 
of  4.6  sq.  yds.  area,  using  a  renovator  of  Type  F.  This  carpet 
was  also  a  Brussels,  with  glue-sized  back,  which  had  been  in 
use  in  the  shoe  department  of  a  large  department  store  in 
Hartford.  These  carpets  contained  approximately  2  oz.  of  dust 
per  square  yard,  none  of  which  was  visible  on  the  surface,  and 
they  were  probably  as  clean  as  the  average  carpet  after  being 

TABLE  1. 
CLEANING  TESTS  OF  DIRTY  CARPETS. 


Type  of 

Renovator. 

A 

C 

F 

Vacuum  in  renovator,  ir 
Air  exhausted,  cu.  ft.  pt 
Material  removed,  per 
1  min  

i.  Hg. 

2 
16 

50 
72 
85 
90 
93 

95 
0.037 
1.9 
0.07 

27  2 
60 
81 
90 
95 
98 

100 

0.147 
2.0 
0.29 

1 
24 

37 
,    52 
59 
61 
66 

67 

0.045 
1.34 
0.06 

37  2 
39 
59 
66 
72 
75 

82 
0.116 
1.64 
0.19 

4 

44 

47 
63 
71 
83 

87 

90 
0.252 
1.8 
0.45 

59/2 

35 
55 
69 
77 
84 

89 
0.261 
1.78 
0.475 

:r  min 
cent. 

of 

total, 

Material 
2  min. 

removed 

,  per 

cent. 

of 

total, 

Material 
3  min. 

removed 

,  per 

cent. 

of 

total, 

Material 
4  min. 

removed 

,  per 

cent. 

of 

total, 

Material 
5  min 

removed 

,  per 

cent. 

of 

total, 

Material 
6  min. 
H.  P.  pe 
Ounces  < 
H.  P.  at 

removed 

,  per 

cent. 

of 

total, 

r  ounce  d 
lust  per  r 
renovato 

ust 

ninute 
r 

THE  CARPET  RENOVATOR 


35 


gone  over  with  a  carpet  sweeper  or  after  a  light  application 
of  a  broom. 

As  the  sizes  of  the  carpets  used  in  making  the  tests  were  not 
always  the  same,  allowance  has  been  made  for  this  variation  by 
using,  in  the  case  of  Type  F  renovator,  instead  of  the  true 
time,  a  calculated  time  which  allows  each  renovator  the  same 
time  for  cleaning  1  sq.  yd.  of  carpet.  For  instance,  in  the  case 
of  the  small  carpet  cleaned  with  Type  F  renovator,  an  interval 
of  60X4.6-=- 6,  or  46  seconds,  was  taken  as  equal  to  one  minute's 
cleaning  of  the  carpet  with  types  A  and  C  renovators.  Such 
interval  is  stated  and  plotted  as  one  minute  in  the  table  opposite, 
which  gives  the  results  of  cleaning  dirty  carpets  with  the  three 
types  of  renovators. 

Type  A  Renovator     Most   Efficient    on    Dirty    Carpets. — 
The  results  of  the  tests  of  the  three  types  of  renovators,  each 


100  r 


|«| 
o 

I  40 


lOz. 


02468 
Time  of  Cleaning,  Minutes 

FIG.   17.      TESTS   OF   THREE   RENOVATORS   ON   DIRTY   CARPETS. 

when  it  was  operated  with  the  highest  vacuum  under  the  reno- 
vator, are  plotted  in  Fig.  17  in  order  that  a  ready  comparison 
may  be  made.  This  curve  indicates  that  Type  A  renovator 
does  more  effective  cleaning  in  less  time  than  either  of  the  other 
two  types  tested. 

Referring  to  the  second  line  of  the  table,  which  gives  the 
degree  of  vacuum  obtained  in  the  renovator  during  the  tests, 
it  will  be  noted  that  the  highest  vacuum  attained  with  each 
type  of  renovator  is  practically  the  same.  This  degree  of 


36  VACUUM    CLEANING    SYSTEMS 

vacuum  was  obtained  with  the  average  vacuum  at  the  hose  cock, 
using  100  ft.  of  hose  in  each  case,  and  corresponds  to  that  ob- 
tained in  the  commercial  operation  of  each  of  the  renovators 
with  the  vacuum  producers  ordinarily  used,  which  was  15  in.  in 
the  case  of  Type  C,  10  in.  in  case  of  Type  A,  and  5  in.  in  case 
of  Type  F,  the  hose  being  the  size  used  by  each  of  the  systems 
as  marketed. 

The  third  line,  which  shows  the  cubic  feet  of  free  air  per 
minute  passing  the  renovator,  indicates  that  Type  A  renovator 
requires  much  less  air  at  the  same  degree  of  vacuum  than 
either  of  the  other  types  to  do  better  'work. 

From  the  readings  in  these  two  lines  the  horse  power  required 
at  the  renovator,  to  move  the  air  that  passes  same  is  obtained 
with  100%  efficiency  adiabatic  compression.  The  results  are 
tabulated  in  the  ninth  line  of  the  table. 

This  indicates  that  Type  A  renovator  does  more  effective 
work  with  about  50%  of  the  power  required  by  either  of  the 
other  types  of  renovators. 

The  tenth  line  gives  the  rate  of  cleaning  and  again  shows 
Type  A  renovator  to  be  the  most  rapid  cleaner. 

The  eleventh  line  gives  the  horse  power  required  at  the  reno- 
vator when  in  operation,  from  which  it  will  be  seen  that  effec- 
tive cleaning  cannot  be  accomplished  with  less  than  J4  H.  P. 
at  the  renovator. 

Attention  is  called  to  the  great  reduction  in  power  in  case  of 
Type  A  renovator  when  the  vacuum  at  the  tool  is  reduced  from 
4^2  in.  to  2  in.  and  to  the  small  reduction  in  the  efficiency 
which  results  from  this  great  reduction  in  power.  This  is 
not  the  case  with  the  Type  C  renovator,  where  there  is  a  con- 
siderable reduction  in  the  already  low  efficiency  with  each 
reduction  in  the  vacuum.  This  characteristic  of  Type  A  reno- 
vator is  discussed  further  on  in  the  chapter  on  hose. 

Tests  of  Carpets  "Artificially"  Soiled.— Having  determined 
the  efficiency  of  the  various  types  of  renovators  when  operated 
on  dirty  carpets,  the  author  then  attempted  to  find  some  sub- 
stance easily  obtained  anywhere  which  could  be  used  as  a  sub- 
stitute for  actual  dirt,  and  which  would  give  approximately 
equal  results  with  these  obtained  on  dirty  carpets. 


THE  CARPET  RENOVATOR  37 

A  test  of  this  character  was  made  by  the  author  some  time 
previous  to  the  tests  of  dirty  carpets  and  was  made  on  a  Wilton 
velvet  rug  of  about  12  sq.  yds.  area.  The  material  spread  on 
same  was  ordinary  wheat  flour,  as  used  in  demonstrations,  3  Ibs. 
of  which  were  placed  on  the  rug  and  rubbed  in  with  sticks  of 
wood  as  well  as  possible  and  the  rug  cleaned  for  three  minutes, 
using  a  Type  A  renovator  attached  to  the  separator  with  50  ft. 
of  1-in.  diameter  hose.  The  results  were  as  follows: 

VACUUM  AT   SEPARATOR,  PER   CENT.   DIKT 

INS.    MERCURY.  REMOVED. 

5  95 

10  98 

15  98 

The  vacuum  at  the  renovator  was  not  measured  at  the  time 
of  making  this  test  and  its  amount  is  not  exactly  known,  but 
further  tests  with  this  type  of  renovator  under  nearly  the  same 
conditions  gave  the  following  results: 

VACUUM  AT  HOSE  COCK,        VACUUM  IN  RENOVATOR, 
INS.  MERCURY.  INS.  MERCURY. 

5  3 

10  6y2 

15  9 

and  it  is  probable  that  the  vacuum  at  the  renovator  during 
these  tests  was  approximately  the  same. 

Comparison  of  the  results  of  this  test,  in  which  4  sq.  yds.  of 
carpet  were  cleaned  per  minute,  wtih  those  of  the  tests  of  dirfy 
carpets,  in  which  only  1  sq.  yd.  was  cleaned  per  minute,  indi- 
cates that  wheat  flour  is  not  a  suitable  substitute  for  dirt  in 
making  a  carpet  cleaning  test. 

The  author,  believing  that  flour  is  of  sufficient  fineness,  but 
not  of  sufficient  weight,  tried  Portland  cement,  which  is  very 
heavy  and  at  the  same  time  exceedingly  fine,  as  a  substitute  for 
dirt  in  soiling  carpets.  The  same  carpet  that  had  been  cleaned 
in  Philadelphia  was  used  and  6^4  oz.  of  cement  was  worked 
into  the  same.  It  was  then  cleaned  with  a  Type  C  renovator, 
with  a  vacuum  of  %y2  in.  hg.  at  the  renovator  and  95%  of  the 
cement  was  removed  in  two  minutes'  cleaning,  as  against  59% 
of  the  dirt  in  the  carpet  when  received. 

Ordinary  dirt,  taken  from  some  flower  pots  which  had  been 


38 


VACUUM    CLEANING    SYSTEMS 


left  dry  for  -some  time,  was  then  tried  with  the  same  carpet, 
using  a  Type  C  renovator  aand  1  in.  hg.  With  this  arrange- 
ment, I\y2  %  of  the  dirt  was  removed  in  two  minutes  as  against 
52%  of  the  dirt  in  the  carpet  as  received. 

This  dirt  was  then  mixed  with  water  to  a  thin  mud  and 
spread  over  the  carpet  and  the  carpet  dried  before  cleaning. 
Then  11/4  oz.  of  this  material  was  worked  into  6  sq.  yds.  of 
carpet  and  a  Type  C  renovator  removed  100%  of  this  in  four 
minutes'  cleaning,  with  a  vacuum  of  2l/2  in.  hg.  at  the  tool  as 
against  12%  of  the  dirt  in  the  carpet  as  received. 

The  author's  ingenuity  being  about  exhausted,  he  referred 
to  the  test  of  Mr.  Stewart  E.  Miller  in  which  quicksand  which 
would  pass  a  50-mesh  to  the  inch  screen  was  used,  a  long- 
napped  Brussels  carpet  being  filled  with  5j^  oz.  per  square 
yard  and  cleaned  with  Types  A  and  C  renovators. 

This  test  indicated  that  a  nearer  approach  to  the  results  in 
cleaning  dirty  carpets  was  possible  with  this  substance  than 
with  any  which  the  author  had  tried.  The  author  repeated  Mr. 
Miller's  test,  using  a  Type  F  renovator,  10-in.  x  J^-in.  cleaning 
slot,  and  also  a  Type  F1  renovator,  15-in.  x  %-in.  to  ^-in. 
cleaning  slot.  In  duplicating  these  tests  the  author  was  asso- 
ciated with  Mr.  E.  L.  Wilson,  a  graduate  of  the  Institute,  who 

TABLE  2. 

CLEANING  TESTS  OF  CARPETS   FILLED  WITH   Sl/2   Oz.  OF   QUICKSAND  PER 
SQUARE  YARD  OF  CARPET. 


Type  of  Renovator. 

A 

C 

F 

F' 

Vacuum  in  renovator  in  hg  

4l/2 

4 

$1A 

3^ 

Air  exhausted,  cubic  feet  per  minute  
Material  removed,  per  cent,  of  total,  1  min. 
Material  removed,  per  cent,  of  total,  2  min. 
Material  removed,  per  cent,  of  total,  3  min. 
Material  removed,  per  cent,  of  total,  4  min. 
Material  removed,  per  cent,  of  total,  5  min. 
Material  removed,  per  cent,  of  total,  6  min. 
H  P  per  ounce  sand 

27 
60 
75 
82 
87 
92 
95 
009 

44 
53 
65 
74 
82 
87 
93 
0  138 

59 
66 
83 
94 
100 

0084 

54 
53 
75 
86 
94 
100 

0109 

Ounces  sand  per  minute  

3.2 

3.1 

5.3 

40 

THE  CARPET  RENOVATOR 


39 


was  familiar  with  the  methods  used  by  Mr.  Miller.  With  his 
assistance,  the  conditions  of  Mr.  Miller's  tests  were  almost  ex- 
actly duplicated.  The  results  of  Mr.  Miller's  and  the  author's 
tests  are  given  in  the  table  opposite,  correction  being  made  in 
the  time  of  cleaning  proportional  to  the  size  of  carpets  used,  to 
allow  the  same  time  for  cleaning  1  sq.  yd.  of  carpet  by  each 
renovator. 

The  results  of  these  tests  are  shown  graphically  in  Fig.  18. 
Comparison  of  these  curves  with  the  curves  of  cleaning  dirty 
carpets  (Fig.  17),  shows  a  falling  off  in  the  efficiency  of  clean- 
ing by  Type  A  renovator  while  there  is  a  gain  in  the  efficiency 
in  cleaning  by  all  of  the  other  types  of  renovators,  Type  C 


02468 
Time  of  Cleaning,  Minutes 

FIG.   18.      CLEANING  TESTS  OF  CARPETS  FILLED  WITH  QUICKSAND. 


being  now  nearly  as  efficient  as  Type  A,  while  Types  F  and  F1 
renovators  are  now  more  efficient  than  Type  A.  This  result 
must  be  due  either  to  the  increased  quantity  of  material  to  be 
removed,  5j/2  oz.  per  square  yard  in  case  of  the  sand  as  against 
2  oz.  per  square  yard  in  case  of  the  dirt,  or  else  to  the  change 
in  the  character  of  the  material  removed,  the  sand  having  much 
sharper  surfaces  than  would  be  encountered  in  case  of  dirt 
which  must  necessarily  be  ground  under  the  feet  before  it 
reaches  the  carpet,  or  to  the  longer  nap  of  the  carpet. 

In  order  to  determine  the  effect  of  the  increase  in  the  quan- 
tity of  material  on  the  results,  the  tests  were  repeated  using 


40  VACUUM    CLEANING    SYSTEMS 

1  oz.  of  sand  per  square  yard  of  carpet  in  each  case,  omitting 
the  test  on  Type  F1  renovator. 

These  tests  were  made  on  a  glue-sized  back,  short  napped 
Brussels  carpet,  using  as  much  sand  as  could  readily  be  worked 
out  of  sight  in  this  carpet.  The  results  of  tests  are  given  in 
the  following  table: 

TABLE  3. 
CLEANING  TESTS  USING  1  OUNCE  OF  SAND  PER  SQUARE  YARD  OF  CARPET. 


Type  of 

Renovator. 

A 

C 

F 

Vacuum  in  renovator,  in.  hg 
Air  exhausted,  cubic  feet  per 
Material  removed,  per  cent. 
1  min.     

2 
16 

48 
70 
91 
100 

0.047 
1.5 

27  2 
54 
87 
100 

0.143 
2.0 

1 
24 

45 
60 
73 
76 

0.06 

37  2 
48 
63 
75 
81 
88 

92 
0.195 
0.92 

4 
44 

50 
65 

77 
88 
97 

102 

0.44 
1.02 

59  ' 
50 
73 
87 
100 

0.223 
2.11 

min  

of  total, 

Material 
2  min 

removed 

,  per 

cent. 

of 

total, 

Material 
3  min 

removed 

,  per 

cent. 

of 

total, 

Material 
4  min. 
Material 
5  min. 

removed 

,  per 

cent. 

of 

total, 

removed 

,   per 

cent. 

of 

total, 

Material 
6  min. 
H.  P.  pe 
Ounces  s 

removed 

,   per 

cent. 

of 

total, 

r  ounce 
and  per 

sand, 
minut 

e 

The  results  of  these  tests  at  the  higher  vacua  are  shown 
graphically  in  Fig.  19.  Comparison  of  these  curves  with  those 
obtained  when  removing  sand  from  a  long  happed  carpet  (Fig. 
18),  shows: 

First,  a  marked  increase  in  the  efficiency  of  Type  A  reno- 
vator, this  being  slightly  better  than  obtained  when  cleaning 
a  dirty  carpet. 

Second,  practically  no  change  in  the  efficiency  of  Type  C 
renovator. 

Third,  a  small  decrease  in  the  efficiency  of  Type  F  renovator, 
which  still  shows  a  much  higher  efficiency  than  when  cleaning 
dirty  carpets. 

In  order  to  determine  how  much,  if  any,  of  these  changes 
in  the  behavior  of  the  renovators  was  due  to  the  increase  in 
the  quantity  of  material  to  be  removed,  the  horizontal  line, 
representing  1  oz.  of  sand  remaining  in  the  long-napped  carpet. 


THE  CARPET  RENOVATOR*  41 

was  drawn  on  Fig.  18  and,  using  this  as  a  base  line,  it  will  be 
seen  that  Type  A  renovator  removes  this  remaining  material 
in  three  minutes,  the  same  time  as  was  required  to  remove  the 
same  amount  from  the  short-napped  carpet.  However,  the  first 
4cl/2  oz.  of  sand  have  been  removed  from  the  long-napped  carpet 
in  three  minutes,  or  at  a  rate  4^2  times  as  fast  as  the  last 
1  oz.  was  removed.  This  indicates  that  the  narrow  slot  reno- 
vator is  capable  of  handling  more  material  than  is  likely  to  be 
encountered  in  any  dirty  carpet  'and  that  the  apparent  decrease 
in  the  efficiency  of  this  renovator  is  not  due  to  the  increased 
quantity  of  material  to  be  removed. 

It  will  be  noted  that  the  Type  C  renovator  removed  the  last 
1  oz.  per  square  yard  from  the  long-napped  carpet  in  the  same 


FIG.    19. 


z          4          6 

Time  of  Cleaning, Minute* 

CLEANING  TESTS  USING  1  OZ.  OF  SAND  PER  SQUARE 
YARD  OF  CARPET. 


time  that  was  required  by  Type  A  renovator,  while  it  needed 
nearly  twice  as  long  to  remove  this  amount  of  material  from 
the  short-napped  carpet  (Fig.  19).  This  renovator,  however, 
was  slower  in  removing  the  first  4^  oz.  per  square  yard. 

,Type  F  renovator  removed  the  last  1  oz.  per  square  yard 
from  the  long-napped  carpet  in  two  minutes,  while  it  required 
twice  this  time  to  remove  the  same  amount  from  the  short- 
napped  carpet.  This  renovator  also  removed  the  first  4^  oz. 
per  square  yard  from  the  long-napped  carpet  in  two  minutes, 
while  it  required  three  minutes  for  Type  A  and  3^4  minutes 


42  VACUUM    CLEANING    SYSTEMS 

for  Type  C  renovators  to  remove  the  same  quantity.  It  is, 
therefore,  evident  that  sand  is  removed  more  rapidly  from  a 
long  than  from  a  short-napped  carpet  when  a  wide  slot  reno- 
vator is  used.  The  same  time  is  required  to  remove  small  quan- 
tities of  sand  from  a  long  or  short-napped  carpet  with  a  nar- 
row slot. 

This  phenomenon  is  probably  due  to  the  sand  being  held  in 
the  carpets  by  the  adhesion  of  its  sharp  edges  to  the  sides  of 
the  nap,  this  being  more  pronounced  in  the  case  of  the  long- 
napped  carpet  where  it  is  easier  to  work  the  material  out  of 
sight  without  grinding  it  into  intimate  contact  with  the  pile 
of  the  carpet.  When  the  wide-slot  renovator  passes  over  the 
carpet,  the  carpet  is  arched  up  into  the  slot  and  the  upper  ends 
of  the  nap  separated.  The  longer  the  nap  or  the  wider  the 
slot,  the  greater  will  be  this  separation.  With  the  long-napped 
carpet  this  separation  will  at  once  release  the  sand,  while,  in 
case  of  the  short  nap,  there  is  less  separation  and  also  more  ad- 
hesion of  the  sand  to  the  pile  of  the  carpet,  due  to  the  harder 
grinding  necessary  to  work  the  material  out  of  sight.  There- 
fore, the  wider  the  cleaning  slot  used,  the  faster  the  sand  will 
be  removed,  as  is  evident  by  comparison  of  the  tests  of  Types 
F  and  F1  renovators  on  the  long-napped  carpet. 

With  the  narrow  slot  renovator  the  arching  of  the  carpet 
under  the  cleaning  slot  is  negligible  and  no  advantage  is  gained 
when  using  this  type  of  renovator  to  remove  sand  from  a  long- 
napped  carpet.  It  is  also  possible  that  the  nap  of  the  carpet 
may  be  longer  than  the  width  of  the  cleaning  slot,  in  which 
case  the  nap  will  not  snap  back  to  a  vertical  position  when  it  is 
under  the  cleaning  slot,  but  will  be  pressed  down  and  will  im- 
pair the  action  of  the  renovator.  The  author  considers  that 
the  width  of  the  slot  should  always  be  greater  than  the  length 
of  the  nap  of  the  carpet  in  order  to  do  effective  cleaning. 

Shortly  after  making  the  above-described  tests,  the  author 
had  occasion  to  make  somewhat  similar  tests,  using  a  sand-filled 
carpet,  in  an  attempt  to  try  out  a  proposed  carpet  cleaning 
test  intended  to  be  used  as  a  standard  for  use  in  specifications 
for  a  vacuum  cleaning  system.  When  a  Wilton  carpet  was 
used,  it  was  found  that  neither  Type  A  or  C  renovator  would 
fulfill  .the  test  requirements,  which  were  within  the  results 


THE  CARPET  RENOVATOR*  43 

obtained  in  tests  already  described.  Unfortunately  a  Type  F 
renovator  was  not  available,  but  the  author  is  of  the  opinion 
that  it  would  have  done  better. 

The  test  was  then  repeated,  using  a  Brussels  carpet  and  the 
test  requirement  was  easily  met.  This  discovery  led  the  author 
to  make  further  tests  of  carpets  of  different  makes,  filled  with 
sand  and  cleaned  under  the  same  conditions  which  yielded  far 
from  uniform  or  satisfactory  results,  and  the  use  of  a  cleaning 
test,  where  artificially-soiled  carpets  are  used,  was  abandoned. 

The  author  is  of  the  opinion  that  no  substance  artificially 
applied  to  a  carpet,  other  than  regular  sweepings,  will  give  any- 
thing like  the  same  results  as  will  be  obtained  in  actual  cleaning. 
Sand  seems  to  be  the  only  substance  which  can  be  worked  into 
the  carpet  that  is  nearly  as  difficult  to  remove  as  the  actual 
dirt  found  in  carpets,  'and,  in  many  cases,  this  material  gives 
results  that  are  misleading  and  unfair  to  some  types  of  reno- 
vators. No  test  which  uses  a  carpet  artificially  soiled  with 
artificially  prepared  dirt  is  considered  to  be  of  any  value  in 
determining  the  relative  efficiency  of  various  types  of  carpet 
renovators. 

A  series  of  tests  was  made  by  Mr.  Sidney  A.  Reeve  con- 
sulting engineer,  of  New  York  City,  in  October,  1910,  at  the 
works  of  the  Vacuum  Cleaner  Company,  Plainfield,  N.  J.,  in 
which  the  conditions  were  such  as  would  give  much  more  uni- 
form results  than  were  possible  in  the  tests  made  by  the  .author. 

In  making  these  tests  the  renovator  was  held  firmly  clamped 
in  any  desired  position  in  a  wooden  carriage  rolling  upon  a 
straight  wooden  track.  The  portion  of  the  carriage  supporting 
the  sweeper  is  attached  to  the  remainder  of  the  carriage  by 
hinges,  so  that  the  sweeper  is  free  to  seek  its  own  contact  with 
the  carpet.  The  carriage  was  given  a  reciprocating  motion  by 
its  attachment  to  a  large  bell  crank,  which  in  turn  received 
its  motion  from  the  factory  shafting.  The  construction  of  the 
bell  crank  was  such  that  the  driving  power  could  be  readily 
thrown  in  and  out  of  gear  at  any  time. 

The  carpet  was  stretched  tightly  upon  a  platen  which  was 
fitted  for  movement  across  the  line  of  motion  of  the  sweeper, 
along  straight  guides  suitably  attached  to  the  floor.  The  ends 


44  VACUUM    CLEANING    SYSTEMS 

of  the  carpet  were  first  wedged  tightly  in  clamps  and  the 
clamps  wedged  apart  so  as  to  stretch  the  carpet. 

The  tests  consisted  in  first  weighing  the  carpet,  then  stretch- 
ing it  upon  the  platen,  then  sprinkling  thereon  a  suitable  and 
known  weight  of  dirt  taken  from  the  separators  of  the  com- 
pany's machines,  from  which  the  lint  and  coarse,  fibrous  ma- 
terial had  been  sifted  and  which  was  thoroughly  trodden  into 
the  fibres  of  the  carpet,  whereupon  the  sweeper  was  set  in  motion 
for  a  given  number  of  strokes. 

In  nearly  all  cases  the  tests  were  repeated  upon  the  same 
piece  of  carpet,  with  the  same  charge  of  dirt,  by  repeatedly 
placing  the  carpet  in  the  frame  and  giving  it  a  further  and 
more  extended  cleaning. 

All  tests  were  corroborated  by  repetition  before  being  ad- 
mitted to  the  records.  Every  effort  was  made  to  have  the  tests 
approach  the  conditions  occurring  in  actual  practice,  as  nearly 
as  possible,  and  still  keep  them  definite  and  measurable. 

The  carpet  used  was  a  Wilton,  of  the  standard  width  of 
27  in.  and  something  over  a  yard  long,  and  the  sweeper  was 
given  a  stroke  of  34  in.  at  the  rate  of  40  strokes  per  minute. 
The  sweepers  were  attached  to  a  6-ft.  tubular  handle,  15/16-in. 
inside  diameter,  and  connected  to  the  separator  by  50  ft.  of 
1-in.  diameter  hose. 

Before  making  any  tests,  the  piston  pump  used  in  the  experi- 
ments was  calibrated  by  pumping  through  a  rotary  meter 
and  the-  amount  of  air  moved  per  revolution  for  each  degree 
of  vacuum  from  open  inlet  to  closed  system  was  carefully  de- 
termined. In  making  the  tests  of  various  renovators,  each  reno- 
vator was  allowed  to  pass  the  same  amount  of  air  as  the  others 
tested  in  comparison  therewith  and  the  vacuum  at  the  reno- 
vator and  at  the  separator  was  allowed  to  be  what  was  neces- 
sary to  pass  this  known  amount  of  air  through  the  renovators. 
This  method  is  widely  different  from  that  used  by  the  author 
where  the  degree  of  vacuum  at  the  renovator  head  was  deter- 
mined and  used  as  a  limiting  factor,  the  quantity  of  air  being 
allowed  to  vary  as  necessary  to  produce  this  vacuum. 

The  results  of  three  series  of  tests  are  given  in  Fig.  20,  which 
shows  those  obtained  with  Kenney  Type  A  renovators,  having 
a  face  12^  in.  x  %  in.  and  a  cleaning  slot  11>2  in.  x  5/32  in. 


THE  CARPET  RENOVATOR 


45 


Curve  A  was  made  with  the  angle  of  the  handle  such  as  would 
give  as  near  as  possible  a  perfect  contact  of  the  sweeper  with 
the  carpet.  Curve  B  was  made  with  the  sweeper  handle  canted 
5°  below  the  proper  angle.  Curve  C  was  made  with  the  sweeper 
handle  raised  approximately  15°  above  the  proper  angle.  The 
ordinates  represented  the  amount  of  dust  in  the  carpet  in 
40ths  of  a  pound,  also  reduced  by  the  author  to  ounces,  and  the 
abscissae  the  number  of  strokes  made  by  the  sweeper. 


0      5      10 


FIG.    20. 


ZO  30          40  50  60 

Number  of  Strokes  o-f  Sweeper 

THREE  SERIES  OF  TESTS  WITH  KENNEY  TYPE  A 
RENOVATORS. 


Curves  B  and  C  show  the  loss  in  efficiency  which  occurs  when 
the  renovator  is  canted  from  its  proper  position  on  the  carpet. 
This  falling  off  in  efficiency  will  necessarily  be  greater  the 
wider  the  face  of  the  renovator,  as  is  shown  in  further  tests 
by  Mr.  Reeve,  using  a  Type  C  renovator,  which  tests  also 
show  that  this  renovator  gives  a  slightly  higher  efficiency 
when  operated  with  the  inrush  slot  stopped,  as  is  shown  in 
Fig.  21. 


46 


VACUUM    CLEANING    SYSTEMS 


In  this  curve  the  ordinates  represent  the  per  cent,  of  normal 
dirt,  i.  e.,  the  amount  likely  to  be  found  in  a  dirty  carpet,  re- 
maining in  the  carpet  at  any  stage  of  the  cleaning,  and  the 
abscissae  the  number  of  strokes  that  have  been  made  by  the 
sweeper.  Heavy  solid  lines  represent  the  results  with  the  inrush 
open  and  dotted  lines  the  results  with  the  inrush  stopped.  The 
figures  on  the  curve  represent  the  degree  to  which  the  handle 
has  been  varied  from  the  position  giving  the  best  results  in 
cleaning. 


is        20         n 

Number  of  JrtroKes  of  Sweeper 

PIG.    21.      TESTS    BY   MR.    REEVE,   USING   TYPE    C     RENOVATOR. 

Fig.  22  shows  the  results  of  tests  by  Mr.  Reeve  using  a  reno- 
vator of  Type  D,  -having  a  double  cleaning  slot,  and  indicate 
that  this  type  of  cleaner  is  not  as  efficient  as  Type  A  and  is 
affected  more  by  the  canting  of  the  handle  from  the  best 
angle  for  cleaning. 

The  above  mentioned  tests  are  published  through  the  courtesy 
of  Messrs.  Ewing  and  Ewing,  attorneys  for  the  Vacuum  Clean- 
er Company. 

Since  the  method  of  making  these  tests  is  entirely  different 
from  that  used  by  the  author,  a  comparison  of  the  results,  with 
any  assurance  that  the  same  conditions  existed  in  both  cases,  is 
impossible.  It  occurred  to  the  author  that  a  comparison  of  the 
results  of  the  tests  by  Mr.  Reeve,  using  a  carpet  artificially 
filled  with  actual  dirt  taken  from  carpets,  with  the  tests  made 
by  the  author  on  carpets  naturally  soiled,  would  tend  to  show 
if  equal  results  could  be  obtained  by  a  vacuum  cleaner  by 
artificially  soiling  a  carpet  with  dirt  taken  from  another  car- 
pet, and  in  cleaning  a  carpet  naturally  soiled. 


THE  CARPET  RENOVATOR  47 

The  author  has  reduced  these  results  to  the  same  units  of 
time  per  square  yard  of  carpet  cleaned  as  in  the  test  on  the 
Philadelphia  carpet  with  the  small-sized  Type  A  renovator 
(11-in.  x  5/2 -in.  face  and  10-in.  x  3/16-in.  cleaning  slot).  The 
carpet  used  by  the  author  contained  6  sq.  yds.  and  was  held 
in  cleaning  by  a  weight  at  each  corner,  while  the  carpet  used 
by  Mr.  Reeve  was  y<\  yd.  wide  and  cleaned  for  approximately 
one  yard  of  its  length,  the  relative  size  being  1  to  8.  The  time 
of  cleaning  was  6  min.  in  the  author's  test  which  would  corre- 


Orictinal  Weight  ofGarpef 


B     10 


FIG.  22. 


50  40  50          60  70 

N  u  m  be  r  of  St  ro  ke  s 
of Sweeper 

TESTS  BY  MR.  REE~VE,  USING  TYPE  D    RENOVATOR. 


spond  to  24-min.  cleaning  in  Mr.  Reeve's  test,  or  30  strokes  of 
the  sweeper.  The  total  dust  in  the  carpet  in  Mr.  Reeve's  test 
was  5/40  Ibs.,  or  2.66  oz.  per  square  yard,  and  his  test  is 
compared  with  the  author's  test  with  the  carpet  containing  2 
oz.  per  square  yard.  Calculation  of  the  per  cent,  of  total 


48  VACUUM  CLEANING  SYSTEMS 

dirt  removed  in  each  5  strokes  of  the  sweeper  in  Mr.  Reeve's 
test,  and  a  comparison  of  the  per  cent,  of  dirt  removed  in  each 
one  minute's  test  by  the  author  are  given  below: 

TABLE  4. 
COMPARISON  OF  TESTS  MADE  BY  MR.  REEVE  AND  BY  THE  AUTHOR. 


MR. 

REEVE'S  TEST. 

AUTHOR'S  TEST. 

Strokes. 

Material 
per  cent 

removed, 
.  of  total. 

Minutes. 

Material  removed, 
per  cent,  of  total. 

S 
10 
15 
20 
25 
30 

62 
80 
89 
94 
97 
99 

1 
2 
3 
4 
5 
6 

60 
81 
90 
95 
98 
100 

The  above  comparison  was  made  using  curve  A,  Fig.  20, 
with  the  sweeper  at  its  best  angle  with  the  floor.  The  close 
agreement  of  the  two  tests  indicates  that  a  carpet  artificially 
soiled  with  dirt  actually  removed  from  another  carpet  by  a 
vacuum  cleaner  is  as  difficult  to  remove  as  dirt  which  has  been 
worked  into  a  carpet  by  ordinary  daily  use.  This  condition 
does  not  result  when  any  other  substance  is  used  to  artificially 
soil  the  carpet,  as  will  readily  be  seen  by  reference  to  the  tests 
of  carpets  filled  with  sand  and  other  substances  which  have 
been  described  in  this  chapter. 

A  comparative  test  of  three  different  renovators  was  recently 
made  by  the  author.  Renovator  No.  1  had  a  cleaning  slot 
14  in.  long  by  ^4  in.  wide,  the  edges  of  the  slot  being  a  seg- 
ment of  a  circle  having  a  >6-in.  radius.  This  form  of  cleaning 
surface  allows  very  small  area  of  contact  with  the  surface 
cleaned  and  permits  the  admission  of  large  air  volumes,  about 
56  cu.  ft.,  with  2-in.  vacuum.  It  is  practically  a  Type  F  reno- 
vator, similar  to  that  used  in  the  tests  at  Hartford. 

Renovator  No.  2  had  a  cleaning  slot  9y2  in.  long  and  l/±  in. 
wide,  the  face  of  the  renovator  being  approximately  %  in. 
wide  and  practically  a  plain  surface,  a  typical  Type  B  reno- 
vator. 

Renovator  No.  3  had  a  cleaning  slot  7%  in.  long  and  l/%  in. 


THE  CARPET  RENOVATOR  49 

wide,   the  face   of   the  renovator  being    %   in.   wide   and   the 
edges  slightly  rounded,  a  typical  Type  A  renovator. 

The  carpet  used  was  a  Colonial  velvet  rug  with  %-iu.  nap, 
closely  woven,  containing  6  sq.  yds.  This  rug  was  filled  with 
12  oz.  of  dirt  taken  from  separators  of  cleaning  machines, 
from  which  the  lint  and  litter  had  been  screened.  This  was 
rubbed  into  the  carpet  until  no  dirt  was  visible  on  the  surface, 
the  surface  being  then  lightly  swept  with  a  brush  and  weighed. 

In  cleaning  this  carpet  the  renovator  was  passed  once  over 
the  entire  surface  at  the  rate  of  about  70  ft.  per  minute.  This 
required  six  strokes  and  50  seconds  for  No.  1  cleaner,  nine 
strokes  and  77  seconds  for  No.  2  cleaner,  and  12  strokes  and 
100  seconds  for  No.  3  cleaner. 

The  carpet  was  then  weighed,  spread  down  and  gone  over 
three  times,  weighed,  spread  down  and  gone  over  four  times. 
This  operation  was  repeated  until  the  carpet  came  within  y2  oz. 
of  its  weight  when  received. 

Each  of  the  three  renovators  was  operated  with  a  vacuum 
of  2  in.  at  the  renovator. 

The  results  of  these  tests  are  illustrated  by  curves  1A,  2A  and 
3A  in  Fig.  23.  This  shows  that  to  remove  95%  of  the  dirt 
the  renovator  had  to  be  passed  over  the  carpet  20  times  for 
No.  1  renovator,  15  times  for  No.  2  renovator  aijd  8  times  for 
No.  3  renovator. 

Similar  tests  were  then  made  with  each  of  the  renovators, 
with  a  vacuum  of  4.5  in.  of  mercury  at  the  renovator.  The 
results  are  shown  by  curves  IB,  2B  and  3B  (Fig.  23)  These 
show  that  to  remove  95%  of  the  dirt  the  renovator  had  to  be 
passed  over  the  carpet  11  times  with  No.  1  renovator,  6^2  times 
with  No.  2>  and  4^  times  with  No.  3. 

These  tests  are  all  on  the  same  carpet,  with  the  same  quan- 
tity of  the  same  dirt  and  with  the  renovators  moved  at  the 
same  speed  in  each  case.  The  comparison  of  the  results  should 
give  a  fair  indication  of  the  efficiency  of  the  different  types 
of  renovators  at  different  degrees  of  vacuum  within  the  reno- 
vator and,  therefore,  form  the  most  conclusive  proof  of  the 
statements  relative  to  the  efficiency  of  renovators  as  given  in 
this  chapter. 

All  cleaning  tests  that  the  author  has  observed  indicate  that 


50 


VACUUM    CLEANING    SYSTEMS 


the  higher  the  vacuum  within  the  renovator  the  more  rapid 
and  effective  the  cleaning,  and  that  the  efficiency  of  the  reno- 
vator is  fully  as  high  with  a  small  as  with  a  large  volume  of 
air  passing  through  the  renovator  and  with  the  same  degree  of 
vacuum  within  same.  Therefore,  the  most  effective  and  eco- 


2  4  <o  8  10  I?  K  16  18          EC 

Times  Over 

FIG.   23.      TESTS    SHOWING   EFFICIENCY   OF    DIFFERENT   TYPES 

OF   RENOVATORS   AT    DIFFERENT    DEGREES 

OP  VACUUM. 

nomical    renovator    should   be    that    which    gives   the    highest 
vacuum  with  the  least  air  passing. 

If  the  degree  of  vacuum  within  the  renovator  be  carried  to 
an  abnormally  high  degree,  there  will  be  a  tendency  for  the 
renovator  to  cling  so  close  to  the  carpet  that  its  operation  will 
be  difficult  and  the  wear  on  the  carpet  rapid.  The  produc- 


THE  CARPET  RENOVATOR 


51 


tion  of  this  high  vacuum,  with  a  larger  quantity  of  air  ex- 
hausted, will  result  in  the  expenditure  of  power  at  the  reno- 
vator in  excess  of  the  gain  in  efficiency  and  speed  of  cleaning. 

It  is  evident  that  the  wider  the  cleaning  slot,  the  greater  will 
be  the  tendency  of  the  renovator  to  stick  to  the  carpet  with  a 
high  vacuum  within  the  same.  The  author  has  experienced  no 
difficulty  in  operating  the  10-in.  renovator,  with  3/16-in.  clean- 
ing slot,  with  a  vacuum  as  high  as  9  in.  of  mercury,  but  wider- 
slot  renovators  always  push  hard  when  any  high  degree  of 
vacuum  exists  within  them. 

Effort  Necessary  to  Operate  Various  Types  of  Renovators. 
—The  author  made  a  series  of  tests  to  determine  the  effort 
necessary  to  operate  the  various  types  of  renovators  under  dif- 
ferent conditions.  In  making  these  tests  the  renovator  was  at- 
tached to  a  spring  balance  and  pulled  along  the  floor,  the  pull 
required  to  move  the  renovator  being  observed  by  the  reading 
of  the  balance.  Three  types  of  renovators  were  used  in  this 
test:  Type  A,  having  a  cleaning  slot  5/16  in.  wide  and  12  in. 
long;  Type  C,  having  a  cleaning  slot  5/16  in.  wide  and  12  in. 
long,  with  an  auxiliary  inrush  slot  l/4  in.  wide  and  12  in.  long; 
Type  F,  having  a  cleaning  slot  24  in-  wide  and  10  in.  long.  The 
results  were  as  follows: 

TABLE  5. 
EFFORT  NECESSARY  TO  OPERATE  CLEANING  TOOLS. 


Kind  of  Carpet. 

Type  of 
Renovator. 

Vacuum  at  Reno- 
vator, In.  Hg. 

Pull, 
Pounds. 

Air,  cu.  ft. 
per  min. 

Brussels   short  

A- 

8 

20 

27 

Napped,  close  back... 

Axminster,  long  nap.. 
Velvet    with  glue 

C 
F 
F 
A 

6Ya 

31A 

V/2 

sy2 

17 
11 
14 
18 

31 
59 
59 
28 

Sized  back  

c 

6l/2 

17 

31 

Velvet,  without  glue  .  . 
Sized  back.  . 

A 

c 

3/2 

1 

15 
12 

40 

45 

Linoleum  

A 

13 

23 

12^2 

C 

1 

10 

40 

It  may  be  noted  that,  when  operating  on  the  Brussels  and 
the  glue-sized  velvet,  the  pull  required  to  move  all  types  of 
renovators  bears  a  direct  ratio  to  the  degree  of  vacuum  under 


52  VACUUM    CLEANING    SYSTEMS 

the  renovator,  and  that  the  quantity  of  air  exhausted  is  the 
same  for  each  renovator  on  either  carpet,  but  different  for  each 
type  of  renovator.  It  is  evident  that,  in  this  case,  very  little 
air  enters  the  renovator  by  passing  up  through  the  carpet,  and 
hence  the  action  of  the  inrush  slot  on  Type  C  renovator  is 
noticeable  only  to  a  slight  degree.  When  operating  on  velvet 
carpet,  without  glue-sized  back,  the  inrush  slot,  in  conjunc- 
tion with  the  greater  quantity  of  air  coming  through  the  car- 
pet, has  caused  the  passage  of  a  large  quantity  of  air,  while 
the  vacuum  maintained  at  the  renovator  is  greatly  reduced 
over  that  which  was  maintained  under  Type  A  renovator  when 
the  same  quantity  of  air  was  passing.  In  this  case,  nearly  all 
of  the  air  entering  Type  A  renovator  came  from  the  under 
side  of  the  carpet.  The  effect  on  the  efficiency  of  cleaning  with 
Type  C  renovator  under  these  conditions  can  readily  be  imag- 
ined, by  reference  to  former  tests,  as  being  greatly  reduced 
over  that  of  Type  A  when  passing  the  same  quantity  of  air. 
With  linoleum,  the  action  of  the  inrush  slot  of  the  Type  C 
renovator  has  again  greatly  reduced  the  vacuum  under  the 
renovator,  although  the  quantity  of  air  is  much  in  excess  of 
that  passing  Type  A  renovator.  The  difference  in  the  behavior 
of  the  renovators  on  different  makes  of  carpet  is  seen  to  be 
due  largely  to  the  difference  in  the  quantity  of  air  which  passes 
up  through  the  carpet  into  the  renovator. 

It  is  evident  that,  with  the  same  degree  of  vacuum  within 
the  renovator,  all  types  are  equally  easy  to  push  and  that,  if 
the  vacuum  within  the  renovator  becomes  higher  than  is  nec- 
essary to  produce  good  cleaning  results,  unnecessary  effort  will 
be  required  to  operate  the  renovator. 

Relative  Damage  to  Carpets  with  Various  Types  of  Reno- 
vators.— A  few  tests  have  been  made  by  the  author  to  deter- 
mine the  relative  damage  to  carpets  with  the  various  types  of 
renovators  in  use  and  it  is  found  that,  when  the  edges  of  the 
renovators  are  made  exceedingly  sharp,  considerable  nap  is 
pulled  out.  However,  if  the  edges  are  made  slightly  rounding 
and  not  too  narrow,  no  undue  wear  will  occur  with  any  of  the 
types  of  renovators  described,  provided  the  vacuum  in  the 
renovator  is  not  permitted  to  become  greater  than  5  in.  of 
mercury. 


THE  CARPET  RENOVATOR  53 

The  author  considers  that  for  best  results  the  vacuum  should 
not  be  less  than  83^2  in.  of  mercury  at  the  renovator  and  that 
at  least  2  in.  is  necessary  to  do  even  fair  work,  while,  to  per- 
mit easy  operation  and  prevent  undue  wear  on  the  carpets,  it 
should  not  be  higher  than  5  in. 

Before  deciding  which  type  of  renovator  will  be  most  eco- 
nomical to  use  in  any  case  the  character  of  the  cleaning  to  be 
done  must  be  considered. 

Of  the  various  types  of  renovators  considered  in  this  chapter, 
Type  C  can  be  dismissed  at  once,  as  it  is  neither  as  effective 
a  dust  remover  as  Types  A  or  F  nor  will  it  remove  litter  any 
more  effectively  than  Type  F.  Tests  of  Type  D  renovator  do 
not  show  as  good  results  as  a  dust  remover  as  Type  A,  nor 
will  it  remove  litter  any  more  effectively.  Type  E  renovator 
is  a  modification  of  Type  C  and  is  not  likely  to  be  any  better. 

The  selection,  therefore,  lies  between  Type  A  and  Type  F 
renovators,  the  former  being  by  far  the  best  dust  remover, 
while  the  latter  will  pick  up  a  limited  amount  of  small  litter, 
such  as  matches,  cigar  and  cigarette  stumps,  and  small  bits  of 
paper.  Where  large  quantities  of  these  articles  are  likely  to 
be  encountered,  it  is  more  important  that  the  renovator  should 
be  capable  of  picking  them  up,  but,  unfortunately,  when  these 
articles  are  met  with,  there  are  also  likely  to  be  much  larger 
articles  present  that  cannot  be  picked  up  by  any  but  a  specially- 
designed  renovator,  and  other  means  must  be  employed  to 
remove  them. 

In  residences,  private  offices  and  nearly  every  place  where 
carpets  or  rugs  are  likely  to  be  used,  waste  baskets  and  cuspidors 
are  provided  and  the  articles  mentioned  are  deposited  in  them 
rather  than  on  the  floor.  Thus,  the  renovator  will  be  required 
to  remove  dust,  cigar  ashes  and  sand  or  mud  only,  all  of  which 
can  be  readily  removed  with  a  Type  A  renovator  with  less  ex- 
penditure of  power  than  with  a  Type  F  renovator. 

Public  places,  such  as  ante-rooms,  reception  rooms  and  other 
offices  to  which  the  general  public  is  admitted  in  great  num- 
bers and  which  are  sometimes  carpeted,  are  likely  to  contain 
articles  which  can  be  picked  up  by  Type  F  renovator  and  not 
by  Type  A.  For  cleaning  such  places,  a  Type  F  renovator  is 
necessary,  although  it  requires  considerably  more  power,  but 


54  VACUUM    CLEANING    SYSTEMS 

the  author  sees  no  reason  why  this  type  of  renovator  should  be 
used  to  the  exclusion  of  Type  A,  even  in  buildings  containing 
rooms  of  this  character.  If  the  building  also  contains  several 
rooms  where  litter  will  not  be  encountered,  the  author  would 
recommend  that  both  types  of  renovators  be  used,  each  in  its 
proper  place,  and  thereby  cause  a  considerable  saving  of  power 
in  cleaning  rooms  where  no  litter  is  encountered. 

For  residence  work  there  is  little  need  of  providing  carpet 
renovators  capable  of  picking  up  litter  and,  also,  there  will  be 
very  little  bare  floor  cleaning  to  be  done,  which  requires  larger 
volumes  of  air.  A  smaller  capacity  exhausting  plant,  there- 
fore, can.be  installed,  if  the  Type  A  renovator  is  adopted. 

In  large  office  buildings  where  all  cleaning  is  done  after  office 
hours,  where  the  building  is  provided  with  its  own  power  plant, 
and  where  speed  of  cleaning  and  ability  to  clean  all  apartments 
with  the  fewest  tools  to  be  carried  by  the  cleaners  is  desired, 
it  appears  to  be  better  to  use  only  Type  F  renovators  for  all 
carpet  work,  as  the  extra  power  required  will  not  be  of  vital 
importance. 

Summing  up  the  matter,  the  author  believes  that  both  Type 
A  and  F  renovators  have  their  uses  in  their  proper  places  but 
that  Type  A  has  the  widest  field  of  usefulness,  yet  it  need  not 
invade  the  field  of  the  other.  He  also  believes  that  this  fact 
will  be  realized  by  manufacturers  in  the  near  future,  when  the 
two  types  of  renovators  will  work  together  side  by  side  for  the 
general  good  of  the  manufacturers  and  the  users. 


CHAPTER  IV.  ;     v  — 

OTHER  RENOVATORS. 

The  renovator  which  is  next  in  importance  to  the  carpet 
renovator  is  that  used  for  cleaning  bare  floors.  The  earliest 
form  of  this  renovator  was  the  oscillating  floor  type  intro- 
duced by  Mr.  Kenney.  This  was  a  modification  of  the  narrow- 
slot  carpet  renovator  introduced  by  him.  The  body  of  same 
was  curved  and  supported  on  two  small  wheels  or  rollers,  with 
the  intention  of  bringing  the  cleaning  slot  close  to  the  surface 
cleaned  without  its  touching  same,  as  indicated  in  Fig.  24. 

This  form  of  renovator  was  found  to  be  impracticable  for 
the  reason  that  any  change  in  the  angle  with  which  the  stem 
or  tube  connecting  the  body  of  the  renovator  with  the  handle 
in  relation  to  the  surface  cleaned  tended  to  make  its  action 


FIG.  24.   EARLY  TYPE  OF  BARE 
FLOOR  RENOVATOR. 


FIG.  25.   LATER  TYPE  OF  BARE 
FLOOR  RENOVATOR. 


ineffective.  If  the  angle  were  made  less  the  distance  between 
the  cleaning  slot  and  the  floor  was  increased,  allowing  the  air 
to  enter  the  cleaning  slot  without  coming  in  contact  with  the 
surface  to  be  cleaned,  or,  if  the  angle  were  made  greater,  it 
would  cause  the  face  of  the  renovator  to  strike  and  damage 
the  surface  of  the  floor. 

The  wheels  or  rollers  on  which  this  renovator  was  mounted, 


56 


VACUUM    CLEANING    SYSTEMS 


being  so  small,  were  subject  to  rapid  wear  both  on  their  faces 
and  in  their  bearings,  and  when  these  wheels  were  slightly  worn 
the  renovator  was  practically  useless.  On  account  of  the  above 
defects  this  form  of  renovator  was  abandoned  shortly  after  its 
introduction. 

The  next  form  of  renovator  to  be  tried  was  a  modification 
of  the  ordinary  soft  bristle  brush,  such  as  had  been  in  general 
use  for  cleaning  hard  wood  floors.  The  bristles  were  arranged 
around  the  edges  of  the  cleaning  slot,  in  the  body,  which  was 
shaped  similar  to  the  slot  in  the  carpet  renovator.  Rubber  or 
leather  curtains  or  skirting,  extending  nearly  to  the  ends  of 
the  bristles,  was  placed  inside  of  these  bristles  in  order  to  cause 
the  air  in  entering  the  body  of  the  renovator  to  come  into 
intimate  contact  with  the  surface  to  be  cleaned.  The  general 
form  of  this  type  is  shown  in  Fig.  25. 


FIG.  26.   ANOTHER  TYPE  OF  BARE  FLOOR  RENOVATOR. 

This  form  of  renovator,  while  more  efficient  than  the  oscil- 
lating floor  type,  still  had  its  faults  in  that  it  had  a  ten- 
dency to  push  the  dirt  along  the  floor  in  front  of  it,  much 
the  same  as  the  floor  brush  from  which  it  was  copied  was 
designed  to  do.  Also,  there  was  too  much  tendency  for  the  air 
to  pass  into  the  body  of  the  renovator  without  coming  into  inti- 
mate contact  with  the  surface  .to  be  cleaned.  While  this  type 
of  floor  renovator  or  a  slight  modification  thereof  is  still  in 


OTHER    RENOVATORS  57 

use  by  several  manufacturers  today,  it  never  has  and  never  will 
be  an  effective  bare  floor  cleaner. 

A  modification  of  this  type  of  bare  floor  renovator,  in  which 
the  bristles  have  been  shortened  and  made  thicker,  the  skirting 
or  flaps  placed  on  the  outside  and  the  stem  provided  with  a 
swivel  joint,  is  shown  in  Fig.  26.  Such  an  arrangement  is 
an  improvement  over  the  former  type  as,  owing  to  its  wider 
and  shorter  mass  of  bristles,  there  is  less  tendency  for  the  air 
to  pass  into  the  body  of  the  renovator  without  coming  into  inti- 
mate contact  with  the  surface  cleaned.  It  is  still  prone  to  push 
its  dirt  before  it  and  is  far  from  being  a  perfect  bare  floor 
cleaner. 

The  next  modification  in  the  bare  floor  renovator  was  the 
abandoning  of  the  bristle  brush  in  favor  of  a  cleaning  surface 
composed  of  felt  as  shown  in  Fig.  27.  In  this  form  of  reno- 


FIG.  27.   BARE  FLOOR  RENOVATOR  WITH  FELT  CLEANING 
SURFACE. 

vator  the  air  entering  the  body  of  the  same  must  pass  either 
between  the  felt  and  the  surface  cleaned  or  through  the  felt 
itself,  and  this  air  quantity  is  small.  Since  this  renovator 
has  a  wider  cleaning  slot  than  the  Type  A  carpet  renovator, 
and,  as  it  is  used  with  the  same  vacuum  producer,  hose  and 
pipe  lines,  a  considerable  degree  of  vacuum  will  be  produced 
under  same,  especially  when  operated  on  polished  floors,  where 
the  conditions  are  nearly  the  same  as  we  observed  with  Type 
A  carpet  renovator  operated  on  linoleum.  With  the  wider 
slot,  the  effort  to  move  these  renovators  becomes  too  great  for 
easy  operation.  This  trouble  can  be  overcome  by  using  a  soft 
grade  of  felt  which  permits  sufficient  air  to  pass  through  its 
open  pores  to  reduce  the  vacuum  under  same  and  permit  easy 
operation.  Unfortunately,  this  felt  is  subject  to  rapid  wear 
when  operated  on  surfaces  as  hard  as  floors  and  its  use  has 


58  VACUUM    CLEANING    SYSTEMS 

been  abandoned  in  favor  of  a  harder  felt.  Openings  are  left 
in  the  felt  to  permit  the  passage  of  sufficient  air  to  reduce  the 
vacuum  in  the  renovator  to  working  limits.  These  slots  have 
taken  many  forms.  In  one  form  the  felt  was  placed  in  alternate 
X  and  diamond  shapes,  glued  to  the  face  with  small  open  spaces 
between  them,  as  illustrated  in  Fig.  28.  However,  as  these 


FIG.    28.      BARE    FLOOR    RENOVATOR    WITH    UNUSUAL    FORM 
OF    SLOT. 

small  pieces  must  be  held  in  place  by  glue,  they  are  easily 
broken  loose  and  the  efficiency  of  the  renovator  impaired. 

Another  method,  which  has  now  become  standard,  is  to  open 
the  ends  of  the  renovator  sufficiently  to  permit  easy  operation. 
This  method  produces  high  velocities  at  these  end  openings 
which  are  very  effective  in  cleaning  close  to  walls  and  in  cor- 
ners, where  large  quantities  of  dust  always  lodge  and  are  re- 
moved with  difficulty  without  these  open  slots. 

The  wear  on  these  felt  faced  renovators  was  found  to  be  so 
rapid  that  hard  felt  or  composition  rubber  strips,  placed  so 
that  the  wear  comes  on  the  edges  of  the  same,  have  been  sub- 
stituted. The  felt  or  rubber  was  screwed  on  to  the  outside  of 
a  metal  shell  and  projected  sufficiently  below  the  face  of  the 
metal  to  permit  considerable  wearing  off  of  same  before  the 


FIG.    29.      BARE     FLOOR    RENOVATOR    WITH    HARD    FELT    OR 
COMPOSITION    RUBBER    STRIPS. 

surface  of  the  metal  came  in  contact  with  the  surface  cleaned. 
When  this  occurs,  the  felt  strips  can  readily  be  replaced  with 
new  ones.  The  ends  are  left  open  about  V2  in.  to  form  an 
inrush  for  the  entering  air.  Such  a  type  is  shown  in  Pig.  29. 
-This  renovator,  in  either  of  the  above-described  forms,  is  a 
great  improvement  over  the  bristle  brush  in  that  the  air  passing 


OTHER    RENOVATORS  59 

into  the  body  'of  the  renovator  must  come  into  intimate  contact 
with  the  surfaces  cleaned,  but  it  still  has  the  disadvantage  of 
tending  to  push  the  dirt  before  it. 

A  modification  of  the  above-described  renovators  has  been 
introduced,  in  which  the  wearing  surface  of  the  renovator, 
which  is  covered  with  felt,  is  rounded  as  shown  in  Fig.  30. 
With  this  form  of  bare  floor  renovator,  the  air  passing  into 
same  is  not  only  brought  into  intimate  contact  with  the  sur- 
face cleaned  but  the  dust  is  also  crowded  under  the  curved 
surface  of  the  renovator  as  the  same  is  pushed  over  the  floor 
and  thus  brought  directly  into  the  path  of  the  air  current. 

The  last  named  type  is  by  far  the  most  effective  for  clean- 
ing either  polished  or  unpolished  floors.  It  must  be  provided, 
however,  with  inrush  slots  in  order  to  prevent  its  sticking  and 
preventing  easy  operation.  When  operated  with  hose  pipe  and 


FIG.   30.      BARE   FLOOR  RENOVATOR  WITH   ROUNDED  WEARING 
SURFACE. 

a  vacuum  producer  necessary  to  produce  2  in.  of  vacuum  in 
Type  A  carpet  renovators,  at  least  30  cu.  ft.  of  air  must  be 
permitted  to  pass  the  renovator.  When  operated  with  systems 
adapted  to  produce  4j^  in.  of  vacuum  in  Type  A  carpet  reno- 
vators, at  least  70  cu.  ft.  of  air  must  pass  the  renovator  in 
order  to  permit  easy  operation. 

This  increase  in  the  air  quantity  without  change  in  the  de- 
gree of  vacuum  in  the  case  of  these  renovators,  is  not  without 
increase  in  efficiency,  as  in  the  case  of  the  carpet  renovators, 
because  large  quantities  of  dust  and  also  small  litter  are  met 
with  much  more  frequently  on  bare  floors  than  on  carpets. 
With  the  increase  in  the  volume  of  air  passing,  it  is  possible 
to  pick  up  much  heavier  articles  than  with  the  smaller  quan- 
tity. It  is  also  possible  to  pull  dust  out  of  deep  cracks  or 


60  VACUUM    CLEANING    SYSTEMS 

from  surfaces  which  are  not  in  contact  with  the  renovator  face, 
such  as  the  spaces  between  the  slats  of  floors  of  trolley  cars. 
This  would  not  be  possible  with  the  small  air  quantity.  The 
use  of  the  larger  quantity  of  air  prohibits  the  use  of  small- 
sized  hose  and  pipe  and,  therefore,  larger  articles  can  be  con- 
veyed through  them.  Where  a  large  amount  of  bare  floor  must 
be  rapidly  cleaned  the  use  of  the  larger  air  quantity  is  recom- 
mended. 

A  renovator  (Fig.  30a)  of  unusual  interest  has  recently  been 
developed  by  The  United  Electric  Company,  known  as  the  Tuec 
school  tool.  This  is  a  bare  floor  tool  open  at  both  ends.  It  is 
made  telescopic  and  is  mounted  on  three  wheels  fitted  with 
spring-actuated  guide  rails  which  are  adjustable  to  the  exact 
distance  between  the  legs  of  school  desks.  A  turbine  motor, 
operated  by  the  air  passing  through  the  renovator,  is  arranged 
to  drive  two  of  the  wheels  by  means  of  worm  gear  and  clutch. 

In  operation  the  tool  is  placed  opposite  the  front  of  a  row 
of  desks.  The  clutch  engaged  on  the  turbine  propels  the  tool 
through  the  space  between  the  desk  legs  to  the  rear  of  the 
room.  When  the  tool  strikes  the  wall  at  the  rear  of  the  room, 
the  clutch  is  disengaged  and  it  is  pulled  back  by  drawing  in  the 
hose.  The  spring-actuated  guides  cause  the  cleaning  slot  to 
lengthen  when  passing  between  the  desk  legs  thereby  cleaning 
these  spaces.  The  tool  is  then  sent  up  the  aisle,  the  wheels 
being  set  so  that  it  hugs  the  left  side  of  the  aisle  when  going 
up  and  the  right  side  when  pulled  back.  The  use  of  this  form 
of  tool  should  result  in  considerable  saving  of  time  in  cleaning 
school  rooms.  Unfortunately,  it  cannot  be  operated  where 
pedestal  stools  are  used. 

For  use  in  cleaning  walls,  ceilings,  and  other  flat  surfaces  of 
similar  character,  the  bristle  brush  is  practically  the  only  form 
of  renovator  used. 

Rubber  skirting  cannot  be  used  on  these  brushes  as  it  is  too 
harsh  for  the  easily-marred  surfaces  encountered  by  this  reno- 
vator, and  cotton  flannel  or  a  very  soft  grade  of  felt  takes  the 
place  thereof.  This  change  in  the  material  used  for  skirting 
results  in  a  greater  short-circuiting  of  the  air  into  the  cleaner 
without  coming  into  intimate  contact  with  the  surface  cleaned 
than  occurs  when  used  with  rubber  or  hard  felt  on  bare  floors. 


OTHER    RENOVATORS  61 

As  the  material  to  be  removed  from  surfaces  of  this  char- 
acter is  very  light  dust,  which  has  simply  settled  on  the  surface 
and  is  not  ground  in,  it  is  very  easy  to  dislodge.  When  a 
bristle  brush,  with  a  small  volume  of  air  passing  through  same, 
is  used  to  remove  this  material,  a  greater  portion  thereof  is 
pushed  off  the  projections  and  other  points  of  lodgment  and 
falls  to  the  floor  from  whence  it  must  be  removed  by  a  second 
operation,  using  a  floor  renovator.  In  fact,  the  use  of  an  ordinary 
bristle  brush,  followed  by  the  use  of  a  floor  renovator,  will 
give  almost  as  good  results  as  the  use  of  a  bristle  wall  brush 
with  a  small  quantity  of  air  passing.  However,  with  a  large 
quantity  of  air  passing  into  the  renovator,  this  light  surface 
dust  will  all  be  picked  up  by  the  rapidly-moving  air  current  and 
effective  cleaning  can  be  accomplished  without  the  renovator 
coming  into  direct  contact  with  the  surface  to  be  cleaned. 

The  author  considers  that  a  different  form  of  renovator  is 
necessary  to  effectively  clean  walls,  ceilings  and  similar  flat 
surfaces,  with  a  small  quantity  of  air  passing  and  would  recom- 
mend the  use  of  some  form  of  renovator  having  a  cleaning  face 
composed  of  cotton  flannel  or  some  other  soft  substance  which 
could  be  moved  over  the  surface  cleaned,  in  intimate  contact 
therewith  and  without  damage  thereto.  With  the  soft,  open 
fibre  of  the  substance  necessary  to  be  used  as  a  working  surface, 
sufficient  air  would  enter  the  renovator  without  resorting  to  the 
use  of  inrush  slots  or  openings  and  much  better  results  would 
be  obtained.  No  such  renovator  has  been  designed  for  this 
purpose  to  date,  for  what  reason  the  author  does  not  know, 
and  until  some  such  renovator  is  produced  a  large  volume'  of  «  / 
air  will  be  necessary  for  cleaning  this  kind  of  surfaces.  fis*  y 

An  illustration  of  this  defect  in  the  wall  brush  was  brought 
to  the  author's  attention  recently  in  watching  a  gang  of  labor- 
ers cleaning  the  walls  in  the  U.  S.  Treasury  Building.  They 
had  at  their  disposal  a  portable  cleaner  of  the  most  efficient 
type,  but  in  lieu  of  using  the  wall  brush  provided  with  same, 
they  were  rubbing  off  the  walls  with  a  cloth  mop  which  had 
been  soaked  in  oil,  then  air-dried,  known  as  the  "dustless 
duster."  This  was  mounted  on  the  end  of  a  pole.  The  work- 
men frequently  cleaned  this  duster  with  the  vacuum  cleaner 
hose  without  any  renovator  attached  thereto.  This  cleaner. 


62 


VACUUM    CLEANING    SYSTEMS 


with  brush  in  use,  passed  approximately  30  cu.  ft.  of  free 
air  per  minute.  It  is  evident  that  these  laborers  had  learned 
by  experience  that  it  was  practically  useless  to  try  to  remove 
dust  from  the  walls  by  the  direct  application  of  the  wall  brush 
to  surfaces  and  were  undoubtedly  accomplishing  much  better 
results  in  the  roundabout  way  they  had  of  necessity  adopted. 

When  carved  or  other  relief  work  is  encountered,  the  round 
bristle  brush,  with  extra  long  bristles  and  cotton  flannel  skirt- 
ing, is  nearly  universally  used.  This  type  of  renovator  is. 
shown  in  Fio\  31. 


FIG.  30a.      THE  TUEC  SCHOOL  TOOL. 


FIG.  31.     ROUND 
BRISTLE  BRUSH 
FOR  CARVED  OR 
OTHER  RELIEF 
WORK. 


Owing  to  the  irregularity  of  such  surfaces,  intimate  contact 
therewith  cannot  be  obtained  and  practically  no  results  will  be 
had  unless  there  is  a  large  quantity  of  air  passing  through 
the  renovator.  When  a  large  quantity  of  air  is  available, 
nearly  as  good  results  in  cleaning  this  character  of  sur- 


FIG.    32.       RUBBER-TIPPED     CORNER     CLEANER     FOR     USE     ON 
CARVED    OR   OTHER    RELIEF    WORK. 

face  can  be  obtained  by  the  use  of  the  straight  rubber-tipped 
corner  cleaner,  with  a  round  opening  about  24  in-  ^n  diameter,, 
as  illustrated  in  Fig.  32.  A  very  high  velocity  will  be  obtained 
through  this  renovator  which  will  pull  the  dust  out  of  inac- 
cessible places.  This  form  of  cleaner  is  also  very  effective  for 
cleaning  the  corners  of  rooms,  where  the  floor  and  walls  inter- 


OTHER    RENOVATORS 


63 


sect,  veritable  dust  catchers  that  they  are,  the  cleaning  of  which 
is  fully  as  important  as  it  is  difficult.  Pigeon  holes  and  other 
small  compartments  in  safes,  desks  and  similar  furniture  can 
be  easily  cleaned  with  this  little  renovator  by  simply  introduc- 
ing it  into  the  front  of  such  compartment. 

To  be  effective,  this  renovator  must  pass  approximately  55 
cu.  ft.  of  air  per  minute  and  will  require  a  vacuum  within  the 
renovator  of  approximately  3^  in.  of  mercury.  Where  only 
a  small  quantity  of  air  is  available,  the  author  considers  that 
it  is  better  to  make  use  of  compressed  air  to  blow  the  dust  out 
of  relief  work,  pigeon  holes,  and  other  inaccessible  places  and 
subsequently  pick  this  dust  up  with  other  forms  of  renovators 
after  it  has  found  lodgment  at  more  accessible  points. 

The  cleaner  which  has  met  with  the  most  disastrous  results 
to  the  surfaces  cleaned  is  the  furniture  or  upholstery  renovator. 
This  has  nearly  always  taken  the  form  of  a  small  carpet  reno- 
vator. The  type  of  upholstery  renovator  used  for  many  years 
by  the  Sanitary  Devices  Manufacturing  Company  is  illustrated 
in  Fig.  33.  This  renovator  had  an  inrush  slot  in  the  center. 


PIG.    33.      EARLY    TYPE    CF    UPHOLSTERY   RENOVATOR. 

separated  from  a  cleaning  slot  on  each  side  by  a  partition  ex- 
tending to  within  1/32  in.  of  the  working  face  of  the  reno- 
vator. It  had  the  hose  connected  into  one  end  which  was  ex- 
tended to  form  a  handle.  With  this  cleaning  tool  it  was 
considered  impossible  to  obtain  a  high  vacuum  within  the  reno- 
vator, as  the  inrush  slots  were  supposed  to  act  as  vacuum 
breakers.  However,  as  the  surface  of  the  upholstery  is  not 
firmly  attached  to  the  furniture  it  could  be  drawn  up  into  the 
cleaner,  closing  the  space  under  the  partitions  and  permitting 
a  high  vacuum  to  be  obtained.  This  caused  the  renovator  to 


64  VACUUM    CLEANING    SYSTEMS 

stick,  but,  owing  to  the  narrow  slot  on  each  side  of  the  inrush, 
the  fabric  was  not  caught. 

Other  manufacturers  used  a  renovator  with  a  single  slot,  hi 
some  cases  as  wide  as  y^  in.,  and  instances  are  on  record  where 
the  coverings  of  the  furniture  have  been  drawn  up  through  the 
cleaning  slot  into  the  renovator  and  wedged  so  tightly  that  it 
was  necessary  to  cut  the  covering  from  the  furniture  in  order 
to  release  the  renovator.  To  overcome  this  difficulty  one  manu- 
facturer constructed  the  renovator  in  two  pieces,  secured  to- 
gether with  screws,  so  that,  in  case  the  renovator  became  caught, 
it  could  be  taken  apart  to  release  the  fabric. 

Many  manufacturers  have  attempted  to  overcome  this  de- 
structive tendency  of  the  straight-slot  upholstery  renovator  by 
inserting  partitions  on  the  cleaning  face  of  the  renovator,  thus 
dividing  the  cleaning  slot  into  a  number  of  small  slots  the  area 
of  each  not  being  sufficiently  large  to  permit  the  drawing  in  of 
the  fabric.  These  cleaners  have  followed  two  general  forms, 
one  having  narrow  slots  running  lengthwise  of  the  cleaner,  as 
illustrated  in  Fig.  34.  This  form  reduces  the  destructive  ten- 


i] 


"No  Cleaning  here 

PIG.  34.   UPHOLSTERY  RENOVATOR  WITH  NARROW  SLOTS  TO 
PREVENT  DAMAGE  TO  FURNITURE. 

dency  to  a  great  extent,  but  does  not  entirely  prevent  drawing 
the  fabric  into  the  renovator.  If  the  partitions  across  the  reno- 
vator be  continuous,  as  indicated  by  the  sketch,  there  will  be 
a  portion  of  the  renovator  which  will  not  do  any  cleaning. 
Another  form  uses  short  slots,  sufficiently  inclined  for  the  top 
of  one  slot  to  overlap  the  bottom  of  its  neighbor,  as  shown  in 
Fig  35.  This  form  of  renovator  is  effective  throughout  its 
entire  length  and  the  small  area  of  each  slot  makes  it  practically 
impossible  to  draw  the  fabric  into  the  cleaning  slot.  It  is  con- 
sidered by  the  author  to  be  superior  to  the  former  type, 
especially  when  cleaning  lace  curtains  or  silk  hangings  or  any 
other  very  light  fabric. 

However,  if  the  exhauster  be  of  such  characteristics  and  the 
hose  and  pipe  lines  be  so  proportioned  that  there  is  practically 


OTHER    RENOVATORS 


65 


a  constant  vacuum  in  the  renovator,  regardless  of  the  quantity 
of  air  passing,  and  provided  this  vacuum  is  not  allowed  to  ex- 
ceed 5  or  6  in.  of  mercury,  no  disastrous  effects  will  be  ex- 
perienced in  cleaning-  light-weight  fabrics  with  a  straight-slot 
renovator  having  a  cleaning  slot  not  over  y±  in-  wide.  The 
use  of  this  type,  in  connection  with  a  system  having  the  above- 
described  characteristics,  is  recommended  whenever  rapid  clean- 
ing is  desired. 

Upholstery  renovators  make  the  most  serviceable  clothing 
cleaners,  while  a  small  type  of  bristle  brush,  not  over  4  in.  long 
and  not  over  $4  in.  wide,  makes  the  most  serviceable  hat  brush. 

An  important  form  of  renovator  is  that  used  for  cleaning  be- 
tween the  sections  and  behind  heating  radiators.  A  piece  of 


PIG.    35.      ANOTHER    TYPE    OF   UPHOLSTERY   RENOVATOR   WITH 
SHORT    SLOTS. 

tubing,  flattened  at  its  outer  end,  is  by  far  the  most  effective 
device  for  this  purpose.  This  renovator,  in  connection,  with 
the  hat  brush  tool,  makes  the  two  best  renovators  for  use  in  the 
library,  effective  cleaning  being  possible  with  not  more  than 
20  cu.  ft.  of  air  per  minute,  but  much  faster  work  can  be  done 
with  larger  quantities. 

Another  form  of  renovator  sometimes  furnished  is  the  small 
hand  brush.     This  is  a  bristle  brush,  approximately  8  in.  long 


FIG.  36.   HAND  BRUSH  TYPE  OF  RENOVATOR. 

and  2  in.  wide,  with  the  hose  connection  made  into  one  end  of 
same,  as  illustrated  in  Fig.  36.  This  renovator  is  useful  for 
cleaning  wooden  furniture,  shelves,  tables,  and  other  horizontal 
surfaces  at  about  hand  height,  but,  owing  to  the  tendency  of 
the  air  to  short  circuit  in  its  way  to  the  body  of  the  renovator, 
it  will  not  do  effective  work  with  small  quantities  of  air. 


66  VACUUM  CLEANING  SYSTEMS 

Many  manufacturers  have  produced  a  special  renovator  for 
cleaning  stairs.  This  has  nearly  always  taken  the  form  of  a 
bristle  brush,  approximately  4  in.  square.  When  renovators 
are  rigidly  attached  to  their  stems,  this  form  of  renovator  is 
convenient  and  almost  a  necessity.  However,  when  swivel  joints 
are  provided,  the  ordinary  carpet  or  bare  floor  renovators  are 
fully  as  convenient,  and,  being  larger,  are  more  rapid  cleaners, 
and  the  stair  renovator  is  unnecessary. 

In  isolated  cases,  where  unusual  cleaning  is  necessary,  such 
as  the  removal  of  cork  dust  from  the  floors  of  a  cork  factory, 
picking  up  telegraph  forms  from  the  floors  of  stock  exchanges, 
picking  up  wrapping  papers  in  watch  factories,  etc.,  special 
forms  of  renovators,  with  large  openings  and  large  capacities 
for  air  exhaustion,  become  necessary.  These  appliances  have 
generally  taken  the  form  similar  to  the  carpet  renovator,  but 
with  much  wider  slots,  the  forward  edges  of  which  are  raised 
slightly  above  the  surface  of  the  floor  when  the  renovator  is  in 
operation.  These  renovators,  being  of  no  use  for  any  other 
purpose  than  that  for  which  they  are  specially  designed,  and 
requiring  quantities  of  air  in  excess  of  those  usually  provided 
for  ordinary  types  of  renovators,  may  be  considered  simply  as 
special  appliances  and  do  not  form  a  part  of  the  outfit  required 
to  be  furnished  with  an  ordinary  cleaning  system. 

Another  class  of  cleaning  which  requires  a  special  system  and 
special  appliances  is  the  renovation  of  furs.  Furs  must  never 
be  brushed,  as  it  tends  to  mat  the  hair  and  produce  an  effect 
opposite  to  renovation.  The  only  agent  suitable  for  renovating 
furs  is  compressed  air  and  the  form  of  renovator  best  suited 
for  this  work  is  a  straight  nozzle,  flattened  at  the  end  with  a 
slot  approximately  4  in.  long  and  not  over  1/32  in.  wide,  from 
which  the  air  escapes  in  a  thin  sheet.  When)  held  at  such  an 
angle  that  the  air  will  impinge  on  the  skin  under  the  hair,  a 
thorough  renovation  of  the  fur  is  possible. 

For  the  renovation  of  pillows  a  hollow  needle,  with  small 
openings  along  its  sides,  supplied  with  compressed  air,  produces 
the  best  results.  The  needle  is  thrust  through  the  cover  into 
the  mass  of  feathers,  the  air  tending  to  loosen  up  the  matted 
feathers  and  to  leave  them  in  practically  the  same  condition  as 
when  the  pillow  was  first  filled. 


OTHER    EENOVATORS  67 

As  the  arrangement  of  the  air  removal  system,  to  permit  it 
being  reversed  from  exhaustion  to  compression,  complicates  the 
outfit  >and  adds  to  its  first  cost,  and  as  cleaning  of  this  char- 
acter is  required  only  at  rare  intervals,  these  renovators  may 
also  be  considered  as  special  and  need  not  be  included  in  the 
average  equipment. 

The  author  considers  that  the  renovator  equipment  for  a  sys- 
tem in  which  from  20  to  30  cu.  ft.  of  air  per  minute  is  ex- 
hausted for  each  renovator  in  operation,  and  which  the  author 
classes  as  a  " small  volume"  system,  should  contain  the  follow- 
ing renovators  in  each  "set"  furnished: 

One  carpet  renovator  with  cleaning  slot  y^  in.  by  12  in.  long. 

One  bare  floor  renovator  12  in.  long,  with  curved  felt- 
covered  face. 

One  wall  renovator  12  in.  long,  with  cotton  flannel  and 
curved  face. 

One  upholstery  renovator  with  slot  ^4  in-  by  4  in. 

One  corner  cleaner. 

One  radiator  cleaner. 

In  addition,  one  or  more  hat  brushes  should  be  included 
with  each  installation. 

The  renovator  equipment  for  a  system  in  which  70  cu.  ft. 
of  air  per  minute  is  exhausted  for  each  renovator  in  operation, 
which  the  author  classes  as  a  "large  volume"  system,  should 
contain  the  following  renovators  in  each  "set"  furnished: 

One  carpet  renovator,  with  slot  ^4  in-  by  15  in. 

One  bare  floor  renovator  15  in.  long,  with  curved  felt-cov- 
ered face. 

One  wall  brush,  with  skirted  bristles  12  in.  long  and  2  in. 
wide. 

One  hand  brush,  with  hose  connection  at  end,  8  in.  long 
and  2  in.  wide. 

One  4-in.  round  brush  for  relief  work. 

One  upholstery  renovator. 

One  corner  cleaner. 

One  radiator  tool. 

At  least  one  hat  brush  with  each  system. 

The  number  of  sets  of  renovators  to  be  furnished  should 
naturally  be  at  least  equal  to  the  number  of  sweepers  which 


68  VACUUM    CLEANING    SYSTEMS 

the  plant  will  handle,  and  in  all  buildings,  except  residences, 
there  should  be  one  set  of  renovators  for  each  floor  of  the 
building.  This  will  be  ample,  except  in  exceedingly  large 
buildings. 

The  wearing  face  of  any  renovator  should  never  be  made  of 
soft  metal,  such  as  brass  or  aluminum,  as  the  action  of  the 
dust  passing  the  face  of  the  renovator,  where  the  velocity  is 
always  the  highest  in  the  system,  will  roughen  these  parts 
and  cause  undue  wear  on  the  surfaces  cleaned.  Stamped  steel 
is  undoubtedly  the  best  material  for  wearing  surface  and  cast- 
iron  ranks  next.  These  are  the  only  materials  which  should 
be  permitted. 


CHAPTER  V. 
STEMS  AND  HANDLES. 

Having  discussed  the  various  forms  of  renovators  in  detail, 
the  next  appliance  to  be  taken  up  is  the  connection  between 
the  renovator  and  the  cleaning  hose,  this  being  the  next  por- 
tion of  the  apparatus  forming  a  conduit  for  the  dust-laden  air 
on  its  way  from  the  renovator  to  the  atmosphere  on  the  exhaust 
side  of  the  vacuum  producer. 

In  order  that  the  renovator  may  be  moved  about  on  the 
surfaces  to  be  cleaned,  a  rigid  handle  must  be  provided  and, 
in  order -that  these  various  surfaces  may  be  reached  while  the 
operator  remains  in  a  standing  position,  it  is  necessary  that 
this  handle  be  of  considerable,  as  well  as  variable,  length.  Also, 
a  passage  for  the  dust-laden  air  must  be  provided  in  connection 
with  this  handle.  These  conditions  are  best  met  by  a  metal  , 
tube,  which  the  author  terms  the  stem. 

These  stems  have  been  made  of  various  metals,  that  first  used 
being  draw^i  brass,  probably  because  it  is  best  suited  to  be 
nickel  plated.  On  the  earlier  systems  they  were  almost  in- 
variably made  of  No.  16-gauge  tubing,  %-in.  outside  diameter, 
and  were  bent  at  their  upper  end  through  an  angle  of  nearly 
135°  in  order  that  the  hose  would  hang  from  the  stem  vertically 
downward,  when  the  stem  was  held  at  an  angle  with  the  floor 
of  45°. 

The  lower  ends  of  these  stems  were  rigidly  attached  to  the 
renovator  in  such  a  manner  as  to  assume  the  above-mentioned 
angle  with  the  floor  when  the  renovator  was  in  the  proper 
position  for  cleaning.  In  order  to  bring  the  curved  portion  of 
the  stem  hand  high,  the  stem  was  made  approximately  5  ft, 
long. 

When  operated  with  Type  A  carpet  renovators,  these  curved 
stems  were  apparently  satisfactory.  However,  when  they  were 
used  in  department  stores,  and  other  places  where  much  bare 

69 


70  VACUUM    CLEANING    SYSTEMS 

floor  cleaning  was  necessary,  the  stems  were  cut  through  at 
the  curved  portion  by  the  sand  blast  action  of  the  dust.  The 
cutting  of  these  stems  in  bare  floor  work,  while  they  were  satis- 
factory in  carpet  cleaning,  indicates  that  the  velocity  in  the 
stem,  due  to  the  large  volume  of  air  passing  the  bare  floor 
renovator,  was  too  great  for  this  soft  metal  to  withstand  the 
impact  of  the  dust  on  the  curved  surface.  With  the  systems 
in  use  at  that  time  no  means  were  provided  to  control  the 
vacuum  at  the  vacuum  producer  and  the  hose  and  pipe  lines 
were  small,  both  of  which  tended  to  cause  a  wide  variation  in 
the  volume  of  air  exhausted  under  various  conditions,  in 
the  character  of  surface  cleaned,  and  in  the  number  of  reno- 
vators in  use.  Therefore,  the  value  of  this  destructive  velocity 
is  not  readily  obtainable.  However,  the  author  considers  that, 
in  extreme  cases,  the  quantity  of  air  passing  through  these 
stems  may  have  been  as  high  as  55  cu.  ft.  per  minute.  As  the 
inside  diameter  of  the  stems  was  24  in-  the  area  was  0.44  sq.  in., 
or  0.00328  sq.  ft.,  and  the  velocity  through  the  stem  was  nearly 
17,000  ft.  per  minute.  With  an  average  air  passage  of  40  cu. 
ft.  per  minute  the  velocity  was  12,200  ft.  per  minute. 

Referring  to  tests  of  carpet  renovators,  Chapter  III,  it  will 
be  noted  that  the  maximum  volume  of  air  passing  through 
carpet  renovators  of  Type  A  was  33  cu.  ft.  per  minute,  which 
gives  a  velocity  of  10,000  ft.  per  minute.  Apparently,  at  this 
velocity,  the  cutting  action,  due  to  the  impact  of  the  dust  on 
the  curved  surfaces,  was  not  severe.  However,  the  author  con- 
siders that  the  maximum  velocity  that  should  be  permitted 
through  these  stems  is  9,000  ft.  per  minute. 

As  the  dirt  picked  up  must  be  lifted  almost  vertically,  the 
velocity  in  the  stem  must  not  become  too  low  or  dirt  will  lodge 
in  the  stem.  Experiments  made  by  the  author  indicate  that 
the  minimum  velocity  should  be  at  least  4,000  ft.  per  minute, 
in  order  to  insure  a  clean  stem  at  all  times. 

Shortly  after  the  introduction  of  vacuum  cleaning,  the  use 
of  drawn-steel  tubing  for  the  manufacture  of  stems  for  clean- 
ing tools  was  standard  with  one  manufacturer  and,  lately,  its 
use  has  become  almost  universal,  except  in  cases  where  very 
long  stems  are  necessary,  as  on  wall  brushes  when  cleaning 


STEMS  AND  HANDLES  71 

very  high  ceilings.  For  such  work,  aluminum  stems  have  been 
adopted. 

This  harder  metal  will  better  withstand  the  cutting  action 
of  the  dust  and  can  also  be  made  much  thinner  and  lighter  in 
weight  than  brass  tubing  of  equal  strength.  These  stems  were 
made  from  1  in.  outside  diameter,  No.  21  gauge  tubing,  having 
an  internal  area  of  0.68  sq.  in.,  and  the  author  does  not  know 
of  any  cases  where  these  stems  have  been  cut  by  the  impact 
of  the  dust. 

Stems  of  this  metal  are  recommended  by  the  author  for  use 
with  all  floor  renovators  and  with  wall  brushes,  except  in 
cases  where  exceedingly  long  stems  are  required,  when  those 
of  drawn  aluminum  tubing  are  recommended. 

For  use  with  Type  A  renovators,  where  the  minimum  air 
quantity  is  approximately  22  cu.  ft.  per  minute,  the  greatest 
area  permissible  is  :dnro  —  0.0055  sq.  ft.,  or  0.79  sq.  in.,  equiva- 
lent to  1-in.  diameter.  With  a  maximum  air  quantity,  under 
proper  control,  of  39  cu.  ft.  per  minute,  the  minimum  area 
will  be  -s-fl-o-  =  0.00433  sq.  ft,  or  0.625  sq.  in.,  equivalent  to 
0.89  in.  diameter,  so  that  a  1-in.  outside  diameter  stem  of  No. 
21  gauge  metal,  having  an  inside  diameter  of  0.932  in.,  is 
recommended. 

For  use  with  a  Type  F  renovator,  with  a  minimum  air  quan- 
tity of  44  cu.  ft.  per  minute,  the  maximum  area  of  the  stem 
will  be  4000  =  0.011  sq.  ft.,  or  1.58  sq.  in.,  equivalent  to  1.4 
in.  diameter,  while,  with  a  maximum  air  quantity  of  70  cu.  ft. 
per  minute,  the  minimum  area  will  be  -^h  =0.0077  sq.  ft., 
or  1.11  sq.  in.,  equivalent  to  1.18  in.  diameter,  and  a  1^4-in. 
diameter  stem  of  No.  21  gauge  metal,  having  an  inside  diam- 
eter of  1.18  in.  is  recommended. 

Tests  of  Mr.  S.  A.  Reeve,  which  are  discussed  in  Chapter 
III,  indicate  that  both  edges  of  the  cleaning  slot  on  any  reno- 
vator must  be  in  contact  with  the  surface  cleaned  in  order  to 
do  effective  cleaning.  A  renovator  which  is  rigidly  connected 
to  its  stem  can  be  effectively  operated  with  the  stem  at  but 
one  angle  with  the  surface  cleaned,  which  makes  the  cleaning 
under  furniture,  or  on  wall  at  various  heights  above  the  floor, 
impossible.  In  order  to  do  effective  cleaning  with  any  degree 


72 


VACUUM    CLEANING    SYSTEMS 


of  speed  and  comfort  to  the  operator,  some  form  of  swivel  joint 
between  the  renovator  and  its  stem  is  necessary. 

These  swivels  have  been  made  in  many  forms,  one  of  which 
consists  of  two  hemispheres  connected  by  a  bolt  on  their  axis, 
as  shown  in  Fig.  37.  This  form  of  swivel  is  unsuited  for  use 
under  these  conditions,  as  lint,  thread  and  any  other  small 
articles  picked  up  will  catch  on  the  bolt  which  lies  directly 
in  the  path  of  the  dust-laden  air  current,  and  its  use  should 
be  prohibited  in  all  cases. 

Another  form  of  swivel,  which  is  must  better  than  the  last 
mentioned,  is  shown  in  the  illustration  of  the  bare  floor  brush, 
Fig.  26,  Chapter  IV,  there  being  no  obstruction  in  the  air 
passage.  However,  these  swivels  are  composed  of  moving  parts 


FIG.    37.      FORM     OF    SWIVEL    JOINT    CONNECTING    STEM    TO 
RENOVATOR. 

which  are  in  contact  with  the  dust-laden  air  and  great  care 
must  be  taken  in  their  design  so  that  in  action  dust  does  not 
lodge  between  the  wearing  surfaces  and  shortly  ruin  the  swivel. 
This  can  be  guarded  against  by  making  any  opening  between 
the  parts  of  the  swivel  point  away  from  the  dust  current,  as 
indicated  in  Fig.  38,  in  which  the  direction  of  the  air  current 
is  indicated  by  the  arrow.  A  slightly  loose  fit  between  the 
wearing  surfaces  will  permit  a  small  leakage  of  air  through  the 
joint  which  will  tend  to  remove  any  dust  which  may  find  its 
way  into  the  joint.  However,  it  is  not  considered  advisable 
either  to  allow  very  much  leakage  through  the  joint,  as  it  re- 
duces the  net  efficiency  of  the  system,  or  to  depend  much  on 


STEMS  AND  HANDLES  73 

the  air  current  through  the  joint  keeping  the  wearing  sur- 
faces clean.  The  swivel  indicated  in  the  illustration  of  the 
floor  brush  does  not  entirely  prevent  the  dust  entering  same 
and  it  permits  the  movement  of  the  stem  in  a  vertical  plane 
only.  On  the  other  hand,  a  swivel  consisting  of  a  45°  elbow, 
rigidly  attached  to  the  stem  and  turning  freely  on  a  horizontal 
spud,  and  fastened  to  the  renovator,  as  shown  in  Fig.  38,  allows 
a  motion  of  the  stem  either  in  a  vertical  plane,  which  will  cause 
the  renovator  to  rotate,  and  enable  the  operator  to  pass  same 
around  or  back  of  legs  of  furniture,  or  a  semi-rotary  motion 
may  be  imparted  to  the  stem,  which  will  permit  the  renovator 


FIG.  38.      SWIVEL  JOINT  ARRANGED  TO  PREVENT  DUST  LODGING 
BETWEEN    THE    WEARING    SURFACES. 


to  move  forward  in  a  straight  line  while  the  angle  which  the 
stem  makes  with  the  floor  will  constantly  decrease.  After  a 
little  practice  the  operator  can  place  a  renovator  equipped  with 
one  of  these  swivels  in  almost  any  position  without  incon- 
venience. Illustrations  of  the  possibilities  of  this  form  of 
swivel  are  presented  in  Figs.  39  and  40,  in  which  an  operator  is 
shown  cleaning  the  treads  and  risers  of  a  stairway  without 
changing  her  position,  and  in  Fig.  41,  where  the  operator  is 
cleaning  the  trim  of  a  door  with  apparent  ease.  The  author 
considers  that  this  form  of  swivel  is  the  only  satisfactory  joint 
between  the  renovator  and  its  stem.  It  is  being  rapidly 
adopted  by  nearly  every  manufacturer  of  vacuum  cleaners. 


74  VACUUM    CLEANING    SYSTEMS 

In  operating  any  renovator  it  is  nearly  always  drawn  back- 
wards and  forwards  in  front  of  the  operator,  across  the  surface 
to  be  cleaned.  When  the  hose  is  rigidly  attached  to  the  upper 
end  of  the  stem,  it  becomes  necessary  to  drag  at  least  a  por- 
tion of  the  cleaning  hose  along  with  the  renovator  when  it  is 
moved  forward,  and  to  crowd  the  same  back  on  itself  when 
the  renovator  is  moved  backward.  This  action  has  a  tendency 


FIG.   39.      SWIVEL  JOINT   IN  USE. 

to  kink  or  snarl  the  hose  about  itself  and  makes  the  operation 
of  the  renovator  very  awkward,  often  causing  the  operator's 
feet  to  become  entangled  in  the  hose. 

This  action  also  brings  an  undue  amount  of  wear  on  the 
hose  near  the  end  which  is  attached  to  the  stem,  as  may  be 
readily  noted  by  inspection  of  hose  used  with  rigidly-attached 
stems.  This  will  show  that  the  end  of  the  hose  is  entirely  worn 
through,  while  the  remainder  of  the  hose  is  still  in  serviceable 
condition. 

The  trouble  above  stated  can  be  overcome  by  providing  a 
swivel  joint  at  the  point  of  connection  between  the  hose  and 


STEMS  AND  HANDLES  75 

the  stern.  A  few  attempts  to  use  a  joint  similar  to  that  first 
described  in  connection  with  the  renovator  and  its  stem,  as 
illustrated  in  Fig.  37,  have  been  made,  but  without  much  suc- 
cess, as  the  bolt  through  the  air  passage  catches  dirt  and  there 
is  not  sufficient  freedom  of  movement  between  the  portions  of 
the  swivel.  Variations  of  this  form  of  joint  have  been  made, 
one  of  which  is  provided  with  a  screwed  union  to  join  the  two 


FIG.    40.      ANOTHER    USE    OF    SWIVEL    JOINT,    SHOWING    POSSI- 
BILITIES   OF    THIS    FORM. 

portions,  as  shown  in  Fig.  42.  This  is  a  much  better  form  than 
that  first  described  and  has  been  successfully  used  in  connec- 
tion with  heavy  1-in.  diameter  hose.  Care  must  be  exercised 
that  the  direction  of  the  flow  of  air  is  always  in  the  direction 
indicated  by  the  arrows  in  the  sketches,  as  a  reversal,  if  only 
for  a  short  time,  will  ruin  the  joint,  due  to  lodgment  of  dust 
in  the  moving  parts. 

Still  another  variation  in  this  form  of  swivel  has  the   two 
main  parts  made  to  fit  one  within  the  other  and  a  snap  ring  is 


76 


VACUUM    CLEANING    SYSTEMS 


placed  in  a  groove  in  the  male  portion  of  the  joint,  this  groove 
being  deep  enough  to  take  the  entire  thickness  of  the  ring. 
The  two  parts  are  then  fitted  together  and  the  ring  snaps  out 
into  a  corresponding  groove  in  the  female  portion  of  the  joint, 
uniting  the  two  parts.  This  joint  gives  a  fairly  free  movement 


FIG.  41.      OPERATOR  CLEANING  TRIM  OF  DOOR  WITH  SWIVEL  JOINT. 

to  the  parts  thereof,  but  has  the  disadvantage  that  it  cannot  be 
taken  apart  without  breaking  one  of  its  parts. 

A  modification  of  this  form  of  swivel  has  been  made  by  the 
manufacturers  of  the  last-described  swivel,  in  which  semi- 
circular grooves  have  been  cut,  one  on  the  inside  of  the  female 


FIG.    42.      SWIVEL    JOINT,   WITH 
SCREWED   UNION. 


FIG.    43.      SWIVEL    JOINT    HAVING 
BALL    BEARINGS. 


STEMS  AND  HANDLES 


77 


portion  and  one  on  the  outside  of  the  male  portion.  Steel  balls 
are  forced  into  this  groove,  after  the  parts  are  assembled, 
through  an  opening  provided  in  the  edges  of  the  parts.  This 
opening  is  closed,  after  the  balls  are  in  place,  by  a  small  pin, 
as  shown  in  Fig.  43.  The  swivel  then  becomes  a  ball-bearing 


FIG.    44.      ACTON    OF   BALL-BEARING    SWIVEL    JOINT. 

joint,  with  a  freedom  of  motion  characteristic  of  such  bearings. 
This  joint  readily  responds  to  every  movement  of  the  stem  and 
keeps  the  hose  hanging  vertically  downward  and  always  free 
from  kinks.  Its  action  is  illustrated  in  Fig.  44,  in  which  it 
is  being  used  in  connection  with  a  carpet  renovator.  This 
joint  is  considered  to  be  the  most  efficient  on  the  market.  It 
is  protected  by  a  patent  controlled  by  a  manufacturer  of 
vacuum  cleaners. 


78  VACUUM    CLEANING    SYSTEMS 

Valves  are  placed  at  the  upper  end  of  the  stems  by  many 
manufacturers,  to  cut  off  the  suction  when  carrying  the  reno- 
vators from  room  to  room,  and  when  it  is  necessary  to  stop 
sweeping  to  move  furniture.  These  valves  have  nearly  always 
taken  the  form  of  a  plug  cock  with  tee  or  knurled  handle.  They 
are  useful  on  large  installations,  where  vacuum  control  is  either 
inherent  in  the  exhauster  or  where  some  means  of  vacuum  con- 
trol is  provided,  as  a  considerable  saving  of  power  may  be 
obtained  by  closing  same,  as  will  be  explained  in  a  later  chap- 
ter, and  to  overcome  the  unpleasant  hissing  noise  caused  by  the 
inrush  of  air  into  the  renovator  when  same  is  held  off  the 
floor. 

When  the  exhauster  has  a  capacity  of  but  one  sweeper  and 
when  the  cleaning  is  done  at  times  when  the  building  is  unoc- 
cupied, there  seems  to  be  little  need  for  this  refinement,  which 
has  two  defects:  first,  the  operators  will  not  close  the  valves: 
second,  when  they  have  been  closed  they  are  only  partly  opened, 
as  indicated  in  Fig.  45.  When  this  occurs,  the  portions  of  the 


FIG.    45.      ILLUSTRATION    OF    DEFECTS    OF    PLUG    COCKS. 

plug,  which  are  shown  stippled,  are  quickly  cut  away  by  the 
sand-blast  action  of  the  dust,  making  it  necessary  to  open  the 
valve  a  still  smaller  amount  the  next  time  it  is  operated,  cutting 
off  still  more  of  the  plug  until  a  new  plug  is  necessary  in  order 
to  make  the  valve  again  operative. 

A  few  attempts  have  been  made  to  overcome  these  defects 
by  making  the  valves  self-closing  and  having  them  so  con- 
structed that  when  the  operator  grasps  the  handle  the  valve 
will  be  forced  wide  open,  on  the  principle  of  the  pistol  grip. 
These  valves  will,  of  course,  close  whenever  the  handle  is  re- 
leased, and  it  is  impossible  to  grasp  the  handle  in  any  degree 


S^TEMS  AND  HANDLES  79 

of  comfort  without  throwing  the  valve  wide  open.  However, 
since  the  valve  is  closed  by  a  spring,  considerable  pressure  must 
be  applied  to  the  handle  in  order  to  keep  it  open  and  it  acts 
similar  to  the  Sandow  dumb  bell  in  producing  fatigue  of  the 
fingers  in  a  short  time;  they  have  not  come  into  general  use. 
The  use  of  valves  in  the  renovator  handle  is  considered  by  the 
author  to  be  an  expense  not  justified  by  the  gain  in  economy 
and  they  are  no  longer  included  in  specifications  prepared 
by  him. 


CHAPTER  VI. 
HOSE. 

The  more  important  steps  in  the  evolution  of  the  modern 
vacuum  cleaning  system  can  each  be  attributed  to  a  change  in 
the  design  or  construction  of  some  one  of  its  component  parts, 
which,  in  their  former  standard  design,  have  acted  as  a  limiting 
factor  governing  the  form  and  size  of  other  and  more  im- 
portant parts  of  the  system. 

That  part  of  the  early  systems  which  played  the  most  im- 
portant role  as  a  limiting  factor  was  one  for  whose  production 
the  builder  of  the  system  had  to  look  to  other  manufacturers: 
namely,  the  flexible  hose  connecting  the  renovator  stem  to  the 
rigid  pipe  lines  and  vacuum  producer. 

The  early  builders  of  vacuum  cleaning  systems  naturally 
adopted  a  standard  article  for  use  as  a  flexible  conduit;  that 
is,  the  vacuum  hose  which  had  been  used  as  suction  lines  for 
pumps  of  various  characters.  For  such  use  it  was  not  necessary 
that  the  hose  be  moved  about  to  any  great  extent  and,  there- 
fore, its  weight  was  not  an  important  factor  and  had  been 
sacrificed  to  strength  to  withstand  collapse  and  the  rough  hand- 
ling to  which  suction  hose  is  subject. 

This  standard  hose  was  built  up  of  many  layers  of  canvas 
wound  around  a  rubber  tube  or  lining.  A  spiral  wire  was  im- 
bedded between  the  layers  of  canvas  to  prevent  collapse  and 
the  whole  was  provided  with  an  outer  covering  of  rubber. 
Generally  five  to  seven  layers  of  canvas  were  used  and  the 
resulting  hose  was  not  highly  flexible. 

When  used  as  a  flexible  conduit  in  connection  with  a  vacuum 
cleaning  system  it  became  necessary  to  constantly  move  the 
hose  back  and  forth  and  around  the  room  to  be  cleaned.  It  was 
also  necessary  to  limit  the  weight  of  the  hose  to  that  which 
could  be  easily  handled  by  one  person.  This  led  to  the  adop- 
tion of  small  sizes  of  the  then  standard  hose,  24-in.  diameter 
being  first  used,  but  soon  this  was  abandoned  in  favor  of  1-in. 
diameter  hose  weighing  nearly  1  Ib.  per  foot  of  length,  which 
is  the  maximum  weight  that  can  be  conveniently  handled  by 

80 


HOSE  81 

one  person.  This  size  hose  has  become  the  standard  for  all 
systems  maintaining  a  vacuum  at  the  separators  of  10.  in  of 
mercury  or  more. 

Owing  to  its  lack  of  flexibility  this  type  of  hose  is  easily 
kinked  and  is  damaged  by  the  pulling  out  of  such  kinks,  caus- 
ing the  tubing  or  lining  to  become  separated  from  the  canvas 
and  to  collapse,  rendering  the  hose  useless.  There  is  also  con- 
siderable wear  at  the  point  of  connection  to  the  stems  of 
renovators,  where  rigid  connections  are  used. 

The  outside  of  this  hose,  being  rubber,  is  always  liberally 
covered  with  soap-stone  when  it  leaves  the  manufacturer,  and 
when  new  hose  is  dragged  about  over  carpets,  it  frequently  soils 
same  to  a  greater  degree  than  they  are  cleaned  by  the  reno- 
vator. W'hen  this  hose  has  been  in  use  about  twice  as  long 
as  is  necessary  to  wear  off  the  soap-stone,  its  appearance 
becomes  far  from  handsome  'and  is  not  considered  to  be  in 
keeping  with  the  nickel-plated  appliances  which  are  furnished 
with  the  cleaning  tools.  To  overcome  this  objection,  an  outer 
braid  has  been  applied  generally  over  the  rubber  coating,  thus 
adding  further  to  its  already  great  weight. 

What  was  perhaps  the  first  type  of  hose  to  be  produced 
especially  for  use  with  vacuum  cleaning  systems  was  that  in 
which  the  fabric  was  woven  in  layers,  instead  of  being  wrapped 
spirally  around  the  central  tube  or  lining.  Steam  was  intro- 
duced into  the  lining,  vulcanizing  the  lining  and  firmly  uniting 
the  whole  mass.  This  hose  was  made  1  in.  in  diameter,  without 
any  metal  re-inforcement,  and  was  covered  with  the  usual  rub- 
ber coating  and  with  braid,  when  ordered.  This  hose  weighed 
12  oz.  per  lineal  foot  and  1-in.  diameter  was  still  the  largest 
that  could  be  easily  handled. 

The  first  attempt  to  produce  a  light-weight  hose  for  use 
with  vacuum  cleaning  systems  was  by  covering  a  spiral  steel 
tape  with  canvas.  The  air  leakage  through  this  hose  was  found 
to  be  so  high  that  its  use  resulted  in  loss  of  efficiency  of  ,the 
cleaning  plant  and  it  was  found  necessary  to  line  the  hose  with 
rubber.  This  rubber-lined  hose  is  made  in  larger  sizes  than 
formerly  used  and  2-in.  diameter  hose  weighs  approximately 
14  oz.  per  lineal  foot.  It  is  also  much  more  flexible  than  the 
1-in.  hose  formerly  used. 

The  introduction  of  this  type  made  it  possible  to  use  larger 


82  VACUUM    CLEANING    SYSTEMS 

hose  in  connection  with  vacuum  cleaning  systems  and  permitted 
the  use  of  a  lower  vacuum  at  the  separators,  with  the  same 
results  at  the  carpet  renovator,  and  a  larger  quantity  of  air 
when  using  the  brushes  and  other  renovators.  Without  this 
type  of  hose  the  low-vacuum,  large-volume  systems  would  be 
impractical. 

Another  type  of  hose  has  been  recently  introduced  in  which 
a  wire  is  woven  into  the  fabric  of  the  hose  and  the  rubber 
lining  vulcanized  into  place  as  already  described.  No  outer 
coating  of  rubber  is  used  and,  therefore,  no  braid  is  necessary. 
This  gives  a  light-weight  hose  of  great  flexibility  and  neat  ap- 
pearance and  is  undoubtedly  the  best  hose  for  residence  work. 
It  is  more  costly  than  the  steel  tape  hose  which  is  recommended 
for  office  building  and  factory  use,  where  appearance  is  not 
important. 

Hose  Couplings. — The  earlier  systems  used  couplings  having 
screw-threaded  ground  joints,  similar  to  those  which  were  then 
in  use  on  hose  intended  to  withstand  pressure.  These  couplings 


FIG.  46.      BAYONET  TYPE  OF  HOSE  COUPLING,  INTRODUCED  BY 
THE   AMERICAN  AIR  CLEANING   COMPANY. 

require  considerable  time  to  connect  and  disconnect  and  the 
threads  are  easily  damaged  by  dragging  the  hose  about.  The 
exposed  metal  parts  of  the  couplings  are  liable  to  scratch  fur- 
niture. 

To  overcome  the  time  required  to  connect  and  disconnect  the 
screw-coupling,  the  American  Air  Cleaning  Company  intro- 
duced the  bayonet  type  of  coupling,  as  illustrated  in  Fig.  46. 
This  coupling  is  not  readily  damaged  by  rough  handling,  but  it 
has  metal  surfaces  exposed  which  will  scratch  furniture. 


HOSE 


83 


Both  of  these  couplings  have  the  disadvantage  that  the 
air  current  in  the  hose  must  always  be  in  the  same  direction 
and  the  same  end  of  the  hose  must  always  be  next  to  the 
renovator  handle.  Both  of  these  features  tend  to  increase  the 
wear  on  the  hose,  and  the  reversal  of  the  air  current  to  re- 
move stoppages  is  not  possible. 

The  coupling  produced  by  the  Sanitary  Devices  Manufactur- 
ing Company  has  a  piece  of  steel  tubing  fitted  into  each  end 
of  the  hose  and  secured  by  means  of  a  brass  slip-coupler  fitting 
over  the  tubing.  All  ends  being  alike,  the  reversal  of  the  hose 
is  possible  with  this  form  of  coupling.  However,  the  metal 
coupler  is  liable  to  mar  furniture  and  sometimes  there  is  trouble 
with  the  couplings  pulling  apart. 

Much  of  the  hose  in  use  today  is  provided  with  "pure  gum" 
ends  are  vulcanized  in  place,  it  is  necessary  to  take  the  hose 
of  metal  tubing  is  slipped  inside  of  these  ends  to  make  a  coup- 
ling. With  this  arrangement  there  is  no  metal  exposed  to  mar 


flG.  47.      ALL  RUBBER  HOSE  COUPLING  USED  BY  THE  SPENCER 
TURBINE   CLEANER   COMPANY. 

furniture  and  the  hose  lengths  are  reversible.  However,  there 
is  some  trouble  from  the  couplings  pulling  apart.  Since  these 
ends  >are  vulcanized  in  place,  it  is  necessary  to  take  the  hose 
to  a  rubber  repair  shop  whenever  the  hose  breaks  back  of  the 
coupling,  which  occurs  frequently  when  rigidly  attached  to  the 


84  VACUUM    CLEANING    SYSTEMS 

stem  of  the  renovator.  These  repair  shops  are  much  more 
numerous  than  a  few  years  ago  and  this  drawback  is  not  a 
serious  one. 

Another  form  of  coupling  used  by  the  Spencer  Turbine 
Cleaner  Company  is  the  all-rubber  male  and  female  end,  as 
illustrated  in  Fig.  47.  This  has  the  advantage  over  the  metal- 
slip  couplings  and  the  coupling  with  pure  gum  ends  in  that 
when  it  is  properly  locked  it  cannot  be  pulled  apart.  It  is 
absolutely  air  tight,  which  is  true  of  no  other  coupling.  But 
it  does  not  permit  the  reversal  of  the  hose  and  is,  therefore, 
recommended  for  use  only  with  hose  of  1)4 -in.  diameter  or 
larger,  where  there  is  less  liability  of  stoppage,  and  where  the 
ball-bearing  swivel  is  used  at  the  connection  to  the  stem,  pre- 
venting excessive  wear  at  this  point.  The  pure  gum  ends, 
with  the  internal-slip  coupler,  is  considered  to  be  the  most 
satisfactory  for  use  in  all  cases,  except  as  above  stated. 

Hose  Friction. — Hose  friction  plays  an  important  part  in  the 
action  of  any  vacuum  cleaning  system.  In  fact,  where  1-in. 
hose  is  used,  it  beeomes  a  limiting  factor  in  the  capacity  of 
the  system  to  perform  some  kinds  of  cleaning. 

There  are  several  tables  of  hose  friction  published  by  the 
manufacturers  of  vacuum  cleaning  systems,  all  of  which  appear 
to  have  been  based  on  a  constant  velocity  within  the  hose  equal 
to  that  which  would  be  obtained  if  the  air  were  at  atmospheric 
pressure  throughout  the  entire  length  of  the  hose.  But  in 
practice  the  air  is  admitted  to  the  hose  from  the  renovator  at 
a  considerably  lower  absolute  pressure  of  from  25  in.  to 
27  in.  of  mercury,  and  is,  therefore,  moving  at  a  higher 
velocity.  As  the  pressure  is  decreased  by  the  friction  loss  in 
the  hose,  the  velocity  constantly  increases  with  the  expansion 
of  the  air. 

The  results  of  many  tests  made  by  the  author  during  the 
past  seven  years,  with  hose  ranging  from  1-in.  to  2-in.  diameter 
and  with  an  entering  vacuum  ranging  from  0  to  7  in.  of  mer- 
cury and  a  friction  loss  of  from  1  in.  to  25  in.  of  mer- 
cury, indicate  a  close  agreement  with  the  formula  given  in 
Prof.  William  Kent's  "Mechanical  Engineer's  Pocketbook, ' ' 
which  is  based  on  the  formula; 


wL 


HOSE  85 

Q  =  free  air  in  cubic  feet  per  minute. 

c  =  a  constant  which  was  determined  by  D  'Arcy  as  approxi- 
mately 60. 

p=the  loss  of  pressure  in  pounds  per  square  inch. 

d  =  the  diameter  of  pipe  in  inches. 

L  =  the  length  of  pipe  in  feet. 

w  =  the  density  of  the  entering  air  in  pounds  per  cubic  foot. 

Reducing  the  pressure  loss  to  inches  of  mercury  and  using 
in  lieu  of  w,  r  which  is  the  ratio  of  the  average  absolute  pres- 
sure in  the  pipe  to  atmospheric  pressure,  this  formula  becomes : 

0=3,03  t/^f"     .         ,  tj 

To  permit  the  rapid  calculation  of  the  air  quantity  which 
can  be  passed  through  a  hose,  the  author  has  prepared  the 
diagram  shown  in  Fig.  48.  To  use  this  table,  look  up  the  fric- 
tion loss  in  the  hose  in  the  right  hand  margin,  pass  along  the 
horizontal  line  to  the  left  until  it  intersects  the  line  inclined 
at  an  angle  of  45°  toward  the  left,  indicating  the  length  of  the 
hose.  From  this  intersection  pass  vertically  to  the  line  in- 
clined at  approximately  30°  toward  the  left,  representing  the 
diameter  of  the  hose.  The  quantity  in  the  left-hand  margin, 
opposite  the  horizontal  passing  through  this  intersection,  repre- 
sents the  quantity  of  air  which  would  pass  through  this  hose 
in  cubic  feet  at  the  average  density  in  the  hose.  To  correct  this 
quantity  to  free  air,  step  off  the  distance  on  the  vertical  line 
from  the  bottom  of  the  table,  representing  the  average  degree 
of  vacuum  in  the  hose,  to  its  intersection  with  the  curved 
line  near  the  bottom  of  table.  Transfer  this  distance  vertically 
downward  on  the  left  hand  margin  from  the  quantity  first 
read  on  this  margin.  The  quantity  opposite  the  lower  end  of 
this  distance  will  be  the  cubic  feet  of  free  air  per  minute  pass- 
ing through  the  hose  under  these  conditions. 

The  line  inclined  towards  the  right,  which  passes  through  the 
intersection  of  lines  representing  hose  diameter,  and  the  hori- 
zontal line  representing  the  cubic  feet  of  air  passing  through 
the  hose  at  actual  density  in  same,  shows  the  actual  velocity 
in  the  hose  in  feet  per  second. 

For  friction  loss  over  10  in.  of  mercury,  use  the  figures 
at  the  right  hand  of  the  lower  margin,  instead  of  those  in  the 
right  hand  margin,  and  pass  vertically  to  the  hose  diameter. 


86 


VACUUM    CLEANING    SYSTEMS 


Free  Air,.  Cu.  Ff.  per.  Minute 


—  ro  <M       _&.      en         — I          3 

Friction  Loss.  In.  Mercury 

FIG.    48.      CHART    FOR    DETERMINING    HOSE    FRICTION. 

Then  proceed  as  before.  As  these  high  frictions  are  seldom 
used  in  practice,  this  departure  has  been  made  in  order  to  re- 
duce the  size  of  the  diagram. 


HOSE  87 

To  illustrate  how  much  the  friction  tables,  based  on  air  at 
atmospheric  density,  vary  from  actual  results,  two  tests  made 
by  the  author  are  given.  In  the  first  test  it  was  desired  to 
pass  68  cu.  ft.  of  free  air  per  minute  through  a  %-in.  diameter 
orifice  at  the  end  of  100  ft.  of  1-in.  diameter  hose.  Tests  on 
larger  hose  showed  that,  to  permit  this  quantity  of  air  to  pass 
through  the  orifice,  a  vacuum  at  the  orifice  of  2.6  in.  mercury 
was  necessary.  The  most  rational  table  the  writer  could  find 
indicated  that  the  friction  loss  in  the  hose  should  be  18  in. 
mercury,  and  the  final  vacuum  necessary  at  the  hose  cock  would 
have  to  be  20.6  in.  mercury.  On  test  it  was  found  that,  with 
24.8  in.  vacuum  at  the  hose  cock,  but  50  cu.  ft.  of  free  air  per 
minute  was  passing,  with  a  vacuum  at  the  orifice  of  1.6  in. 
mercury,  showing  a  friction  loss  of  23.2  in.  mercury.  With  the 
smaller  quantity  of  air  passing,  the  same  friction  table  indicated 
a  friction  loss,  with  this  quantity  of  air,  of  but  9.8  in.  mercury, 
or  39%  of  that  actually  observed.  Checking  the  results  of  the 
test  with  the  diagram  (Fig.  48)  gives  50  cu.  ft.  of  free  air, 
with  a  friction  loss  of  23  in.  mercury. 

To  illustrate  more  clearly  the  effect  of  the  increase  of  ve- 
locity on  the  friction  loss,  the  actual  vacuum  in  the  hose  has 
been  computed  for  each  10  ft.  of  its  length  and  curves  drawn 
through  these  points.  The  results  are  shown  in  Fig.  49.  The 
straight  line  indicates  the  vacuum  which  should  exist  were  the 
velocity  in  the  hose  constant  throughout  its  length,  and  the 
curved  line  shows  the  vacuum  in  the  hose  when  the  effect  of 
the  increasing  velocity,  due  to  the  rarefaction  of  the  air,  is  con- 
sidered. The  wide  variation  in  the  results  shows  clearly  the 
error  in  the  former  assumption  of  a  constant  velocity  in  the 
hose  throughout  its  length. 

Another  test,  in  which  44  cu.  ft.  of  free  air  was  passed 
through  100  ft.  of  1-in.  diameter  hose,  is  shown  graphically  in 
Fig.  50,  which  discloses  that  the  assumption  of  a  constant  velo- 
city in  the  hose  produces  an  error  of  35%  in  the  results,  indi- 
cating a  loss  of  but  7.8  in.,  when  the  actual  loss  is  12  in.  mercury. 

Naturally,  the  lower  the  final  vacuum  at  the  hose  cock,  the 
less  will  be  the  error  due  to  the  assumption  of  constant  velocity 
in  the  hose.  Tests  with  1^-in.  hose  gave  results  which  agree 


88 


VACUUM    CLEANING    SYSTEMS 


substantially  with  the  result  given  in  tables  already  published, 
and  it  was  this  condition  that  led  to  the  discovery  of  the  error 
in  the  assumption  stated. 


24 


X 


s 

fit 

D 

58 

5 


10         20         30         40         50         60         70 
Length  of  Hose,   Feet 


80 


90        100 


FIG.    49.     EFFECT    OF   INCREASE    OF   VELOCITY   ON   THE 
FRICTION    LOSS. 

Effect  of  Hose  Friction. — As  any  increase  in  the  degree  of 
vacuum  necessary  to  be  maintained  at  the  vacuum  producer 
over  that  maintained  within  the  renovator  requires  a  greater 
expenditure  of  power,  without  any  increase  in  the  efficiency 
or  speed  of  cleaning,  it  is  essential  that  the  friction  loss  in  the 
air  conduit  from  the  renovator  to  the  vacuum  producer  should 
be  made  as  small  as  possible.  The  friction  loss  in  the  hose  is 
the  greatest  loss  in  any  part  of  the  system,  being  the  smallest 
in  diameter,  and  its  reduction  to  the  lowest  figure  possible  is 
of  vital  importance. 

Take,  for  example,  the  use  of  a  Type  A  renovator  with  a 
vacuum  within  the  renovator  of  4^  in.  mercury  and  with  29 
cu.  ft.  of  air  passing  through  same.  The  friction  loss,  with  vary- 
ing lengths  of  different-sized  hose,  will  be  as  follows : 


HOSE 


89 


TABLE  6. 

VACUUM  AT  HOSE  COCK  WITH  TYPE  A  RENOVATORS  AND  WITH  VARYING 
LENGTHS  OF  DIFFERENT-SIZED  HOSE. 


Size  of  Hose. 
In.  Diameter. 

Length, 

in  Feet. 

100 

75 

50 

25 

Vacuum  at 

hose  cock,  in.  hg. 

1 
Jr/ 
|ig 

10 
6 
5.0 

5.72 
4.85 

7 
5.25 
4.75 

4.85 
4.62 

This  indicates,  first,  that  a  much  lower  friction  loss  will 
result  with  the  use  of  larger  hose  than  is  the  case  with  the 
smaller  size.  Note,  also,  that  the  difference  in  the  final  vacuum 
at  the  hose  cock  is  much  more  uniform  when  the  larger-sized 


10       20 


30         40         50         60         70 
Length  of  Hose,  Feet 


80 


100 


FIG.   50. 


ANOTHER   TEST    SHOWING  FRICTION    LOSS    DUE    TO 
VELOCITY. 


hose  is  used  in  varying  lengths.  Since  it  is  desired  to  main- 
tain a  constant  vacuum  at  the  renovator  at  all  times  and  it  is 
also  desirable  to  be  able  to  vary  the  length  of  hose  to  suit  the 
conditions  of  the  work,  while  it  is  not  convenient  to  vary  the 
vacuum  at  the  hose  cock,  much  more  uniform  results  will  be 
possible  when  larger  hose  is  used.  If  the  smaller  hose  is  used  in 
varying  lengths  and  a  practically  uniform  vacuum  is  main- 
tained at  the  hose  cock,  the  quantity  of  air  and  the  vacuum 
at  the  renovator  will  vary.  If  1-in.  hose  is  used  and  the  vacuum 
at  the  hose  cock  be  maintained  at  10  in.  mercury,  the  air  quan- 
tities and  vacuum  at  the  renovator  will  be  approximately: 


90 


VACUUM    CLEANING    SYSTEMS 


TABLE  7. 

AIR  QUANTITIES  AND  VACUUM  AT  RENOVATOR  WITH  I-IN.  HOSE  AND  10-iN. 
VACUUM  AT  HOSE  COCK. 


Length  of  Hose, 
feet. 

Vacuum  at  Renovator, 
in.  hg. 

Air,  cu.  ft. 

H.  P.  at  Hose  Cock. 

100 
75 
50 
25 

V/2 
5 
61A 

7/2 

29 
32 
34 
37 

0.80 
0.885 
0.94 
1.02 

From  this  it  is  evident  that  the  vacuum  within  the  renovator 
will  be  increased  above  that  necessary  for  economical  cleaning. 
It  will  require  somewhat  more  effort  to  push  the  cleaner  over 
the  carpet  and  also  a  slightly  greater  expenditure  of  power  at 
the  hose  cock  to  operate  the  cleaner  with  a  short  than  with  a 
long  hose.  However,  the  author  does  not  consider  that  either 
the  increase  of  effort  to  push  the  renovator  or  the  increase  of 
power  will  be  sufficient  to  prohibit  the  use  of  1-in.  hose  with 
the  Type  A  renovator. 

If  we  use  1^4-in.  hose  with  Type  A  renovator  and  maintain 
a  vacuum  of  6  in.  of  mercury  at  the  hose  cock,  the  resulting 
vacuum  and  air  displacement  at  the  renovator  will  be: 

TABLE  8. 

AIR  QUANTITIES  AND  VACUUM  AT  RENOVATOR  WITH  I^-IN.  HOSE  AND  6-iN. 
VACUUM  AT  HOSE  COCK. 


Length  of  Hose, 
feet. 

Vacuum  at  Renovator, 
in.  hg. 

Air,  cu.  ft. 

H.  P.  at  Hose  Cock. 

100 
75 
50 
25 

4'/2 

4.7 
5.0 

5.4 

29 

30 
33 

35 

0.43 
0.445 
0.448 
0.518 

This  table  shows  a  more  uniform  degree  of  vacuum  at  the 
renovator  with  the  varying  length  of  hose,  but  the  greatest 
difference  is  in  the  horse  power  required  at  the  hose  cock  to 
accomplish  the  same  results  at  the  renovator. 

If  we  use  \l/2-m.  hose  with  Type  A  renovator,  the  vacuum 
at  the  hose  cock  can  be  reduced  to  5  in.  mercury  and  a  prac- 
tically constant  vacuum  will  be  obtained  at  the  renovator,  with 
an  expenditure  of  0.36  H.  P.  at  the  hose  cock. 


HOSE  91 

With  the  Type  C  renovator  where  the  vacuum  within  the 
renovator  is  maintained  at  4  in.  mercury,  with  44  cu.  ft.  of  free 
air  per  minute  passing  through  the  renovator,  the  resulting 
vacuum  at  the  hose  cock,  with  various  lengths  of  the  three  sizes 
of  hose,  will  be  as  follows: 

TABLE  9. 

VACUUM  AT  HOSE  COCK,  WITH  TYPE  C  RENOVATORS  AND  VARIOUS  LENGTHS 
OF  THREE  SIZES  OF  HOSE. 


Size  of  Hose, 
In.  Diameter. 

Length,  in  Feet. 

100 

75 

50 

25 

Vacuum  at 

hose  cock,  in.   hg. 

1 

IX 

V/2 

19 
7.5 
5.1 

14 

6.25 
4.80 

10 

5.5 
4.50 

6.7 
4.7 

4.25 

Referring  to  Fig.  17,  Chapter  III,  it  will  be  noted  that  Type 
C  renovator  will  not  accomplish  much  in  the  way  of  cleaning 
with  a  vacuum  in  the  renovator  lower  than  4  in.  mercury.  There- 
fore, if  we  use  this  type  of  renovator,  with  1-in.  diameter 
hose,  its  length  should  be  limited  to  50  ft.,  for  if  we  use  a 
vacuum  higher  than  10  in.  at  the  hose  cock,  there  will  be  too 
much  increase  in  the  vacuum  at  the  renovator  when  short  hose 
is  used  to  allow  easy  operation,  and  if  we  use  longer  hose  with 
10-in.  vacuum  at  the  hose  cock,  there  will  be  a  reduction  in  the 
vacuum  at  the  renovator  and  effective  cleaning  cannot  be  ac- 
complished. Also,  the  power  required  at  the  hose  cock  to  pass 
44  cu.  ft.  of  air,  with  a  vacuum  of  19  in.  mercury,  required  to 
produce  a  vacuum  of  4  in.  at  the  renovator  with  100  ft.  of  1-in. 
hose,  will  be  3.3  H.  P.,  which  is  prohibitive  when  compared  with 
that  required  with  the  use  of  larger  hose,  i.  e.,  0.825  H.  P. 
with  Ij4-m.  hose  and  0.59  H.  P.  with  1^-in.  hose. 

The  Type  F  renovators  tested  by  the  author  will  show  even 
wider  variations  in  the  vacuum  required  at  the  hose  cock  with 
the  various  lengths  and  diameters  of  hose  than  is  given  for 
Type  C  renovator.  However,  the  type  F  renovator,  which  is 
now  used  by  the  Spencer  Turbine  Cleaner  Company,  having  a 
cleaning  slot  15  in.  long  and  J/2  in.  wide  throughout  its  length. 


92  VACUUM    CLEANING    SYSTEMS 

passes  44  cu.  ft.  of  free  air  per  minute,  with  a  vacuum  under 
the  renovator  of  4  in.  mercury  and  the  resulting  vacuum  at  the 
hose  cock  will  be  the  same  as  that  given  in  the  case  of  the  Type 
C  renovator. 

When  a  bare  floor  renovator  of  the  bristle-brush  type  is  at- 
tached to  the  hose,  the  effect  is  practically  the  same  as  when 
the  end  of  the  hose  is  left  wide  open,  as  the  open  character  of 
the  brush  prevents  the  formation  of  any  vacuum  in  the  reno- 
vator. Therefore,  sufficient  air  must  pass  through  the  reno- 
vator to  create  a  friction  loss  in  the  hose  equal  to  the  vacuum 
at  the  hose  cock. 

As  practically  all  systems  are  arranged  to  maintain  a  con- 
stant vacuum  at  the  vacuum  producer  and  as  the  pipe  friction 
is  generally  less  than  the  hose  friction,  the  vacuum  at  the  hose 
cock  will  be  practically  the  same  when  operating  a  floor  brush 
as  with  a  carpet  renovator. 

Assuming  that  10  in.  mercury  is  maintained  at  the  hose  cock 
with  1-in  hose,  6  in.  with  1^4-in.  hose,  and  5  in.  with  lj/2-in. 
hose,  the  quantity  of  air  which  will  pass  through  a  floor  brush 
with  various  sizes  and  lengths  of  hose  will  be: 

TABLE  10. 

Am  QUANTITIES  THROUGH  FLOOR  BRUSH  OPERATED  IN  CONJUNCTION  WITH 
TYPE  A  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Hose  Length, 

in  Feet. 

100 

75 

50 

25 

Cubic  feet  of  free 

air  per  minute. 

1 
1'4 
W* 

42 
62 
95 

48 
72 
110 

60 
86 
135 

86 
125 
190 

The  quantities  given  for  the  shorter  hose  lengths  are  higher 
than  will  be  observed  in  actual  practice,  due  to  the  increase  in 
the  pipe  friction,  which  will  depend  on  the  length  of  the  pipe 
lines.  However,  the  results  will  illustrate  the  great  increase 
in  the  quantity  of  air  which  will  pass  these  bare  floor  brushes 
when  operated  on  the  same  system  with  carpet  renovators.  If 
the  same  number  of  bare  floor  renovators  are  to  be  used  at 
one  time  as  there  will  be  carpet  renovators  at  some  other  time. 


HOSE  93 

that  is,  if  the  sweeper  capacity  must  be  maintained  when  using 
bare  floor  brushes  as  when  using  carpet  renovators,  a  much 
larger  air  exhausting  plant  must  be  installed  than  would  be 
necessary  to  operate  that  number  of  carpet  renovators. 

If  it  were  possible  to  so  arrange  the  schedule  of  cleaning 
operations  that  bare  floor  brushes  were  never  used  at  the  same 
time  as  carpet  renovators,  the  vacuum  at  the  machine  might  be 
reduced  when  operating  the  floor  brushes  to  a  point  that  would 
reduce  the  quantity  of  air  passing  to  within  the  capacity  of  a 
machine  designed  to  operate  the  same  number  of  carpet  reno- 
vators. Unfortunately,  this  condition  rarely  exists  and,  there- 
fore, the  vacuum  must  be  maintained  at  the  degree  necessary 
to  operate  the  carpet  renovators  that  may  be  in  use  at  the 
same  time  with  the  floor  brushes. 

It  is  also  evident  that  if  the  length  of  hose  used  with  bare 
floor  brushes  could  be  limited  to  the  maximum  ever  used  with 
the  carpet  renovators,  a  reduction  in  the  capacity  of  the  ex- 
hauster necessary  could  be  made.  This  is  another  condition 
which  the  designer  of  the  system  cannot  control. 

Most  Economical  Hose  Size  for  Carpet  and  Floor  Reno- 
vators.— The  horse  power  required  at  the  hose  cock  to  operate 
the  bare  floor  brushes  with  each  of  the  different  sizes  and 
lengths  of  hose  is: 

TABLE  11. 

HORSE  POWER  REQUIRED  AT  HOSE  COCK  TO  OPERATE  BARE  FLOOR  BRUSHES 
IN  CONJUNCTION  WITH  TYPE  A  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Length, 

in  Feet. 

100 

75 

50 

25 

Horse  power 

at  hose  cock. 

1 
1*4 

m 

1.16 

0.92 
1.15 

1.32 
1.06 
1.32 

1.65 
1.27 
1.62 

2.38 
1.38 
2.28 

This  shows  that  where  bare  floor  or  wall  brushes  of  the  bristle 
type  are  used  in  conjunction  with  carpet  renovators  on  any 
system  and  with  Type  A  carpet  renovator,  1^4 -in.  diameter 
hose  will  give  the  lowest  power  consumption. 


94  VACUUM    CLEANING    SYSTEMS 

When  either  Type  C  or  F  renovator  is  used  in  combination 
with  bristle-type  brushes,  the  use  of  1-in.  diameter  hose  must 
be  abandoned  in  lengths  over  50  ft.  and  the  vacuum  at  the  hose 
cock  must  be  maintained  at  10  in.  mercury.  With  1^4-in.  hose, 
it  will  be  necessary  to  maintain  a  vacuum  at  the  hose  cock  of 
7  in.  mercury,  and,  with  1^-in.  hose,  5  in.  will  be  sufficient,  pro- 
vided we  continue  to  use  100  ft.  of  hose  in  the  case  of  the  larger 
sizes.  The  free  air  passing  a  brush  type  of  bare  floor  reno- 
vator under  these  conditions  will  be : 

TABLE  12. 

FREE  AIR  PASSING  BRUSH  TYPE  OF  BARE  FLOOR  RENOVATOR  OPERATED  IN 
CONJUNCTION  WITH  TYPE  C  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Length,  in  Feet. 

100 

75 

50 

25 

Cubic  feet  of  free 

air  per 

minute. 

1 

w 

M 

42 
68 
95 

48 
76 
110 

60 
92 
135 

86 
130 
190 

This  shows  an  increase  in  the  volume  of  air  passing  the  floor 
brush  with  1^4 -in.  hose,-  while  a  higher  vacuum  is  now  carried 
at  the  hose  cock  than  was  necessary  when  Type  A  renovator 
was  used  in  conjunction  with  the  bristle-type  of  floor  renovator. 
The  horse  power  at  the  hose  cock  will  now  be: 

TABLE  13. 

HORSE  POWER  AT  HOSE  COCK  WITH  BRUSH  TYPE  OF  BARE  FLOOR  RENOVATOR 
OPERATED  IN  CONJUNCTION  WITH  TYPE  C  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Length,  in 

Feet. 

100 

75 

50 

25 

Horse  power  at 

hose  cock. 

1 

i# 
i| 

1.16 
1.19 
1.15 

1.32 
1.36 
1.32 

1.65 
1.60 
1.62 

2.38 
2.26 
2.28 

With  this  combination  of  floor  and  carpet  renovators,  there 
is  no  difference  in  the  power  consumption  when  any  one  of  the 
three  sizes  of  hose  is  used.  However,  there  is  a  considerable 


HOSE  95 

increase  in  the  quantity  of  air  passing  the  larger  hose.  This 
leads  to  the  statement  made  by  some  manufacturers  that  this 
increase  in  air  volume  results  in  more  efficient  cleaning. 

Tests  given  in  Chapter  III  indicate  that  increase  in  air  vol- 
ume does  not  result  in  any  more  rapid  or  efficient  cleaning  of 
carpets.  The  results  of  actual  use  of  the  bare  floor  brush  of 
the  bristle  type  show  no  gain  when  cleaning  bare  floors.  As 
stated  in  Chapter  IV,  the  felt-faced  renovator,  being  more 
effective  while  it  requires  less  air.  In  other  words,  it  is  the 
degree  of  vacuum  within  the  cleaner  and  not  the  quantity  of 
air  which  produces  the  cleaning  in  all  cases  where  any  degree 
of  vacuum  is  possible.  When  intimate  contact  between  the 
cleaner  and  the  surface  cleaned  cannot  be  had,  the  volume  of  air 
determines  the  efficiency  of  cleaning.  However,  the  author 
does  not  consider  that  an  exhaustion  of  more  than  60  to  70 
cu.  ft.  of  free  air  through  cleaners  of  this  type  will  increase 
the  efficiency  to  such  an  extent  as  to  justify  the  increase  of 
power  necessary  to  adapt  a  system  to  larger  volumes. 

The  author  considers  that  with  a  system  in  which  brushes 
of  the  bristle  type  are  to  be  used,  the  exhauster  should  have 
a  capacity  of  70  cu.  ft.  of  free  air  per  minute.  Such  a  system 
is  termed  by  the  author  a  " large  volume  system,"  as  already 
mentioned  in  Chapter  IV. 

When  the  felt-covered  floor  renovator  is  used  instead  of  the 
brush,  the  vacuum  within  this  renovator  must  not  be  permitted 
to  rise  above  2  in.  or  the  operation  of  the  renovator  on  the 
floor  will  be  difficult.  To  accomplish  this,  it  is  necessary  to 
provide  openings  in  the  ends  of  the  cleaning  slot,  as  has  been 
explained  in  Chapter  IV.  If  the  vacuum  at  the  hose  cock  be 
assumed  as  10  in.  with  1-in  hose,  6  in.  with  1^4 -in.  hose,  and 
5  in.  with  1^2 -in.  hose,  and  the  vacuum  within  the  felt-covered 
floor  renovator  be  maintained  at  2  in.  mercury  the  cubic  feet  of 
free  air  passing  the  renovator  with  the  various  sizes  and  lengths 
of  hose  will  be: 


96 


VACUUM    CLEANING    SYSTEMS 


TABLE  14. 


CUBIC  FEET  OF  FREE  AIR  PASSING  THE  FELT-COVERED  FLOOR  RENOVATORS 
OPERATED  IN  CONJUNCTION  WITH  TYPE  A  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Length, 

in  Feet. 

100 

75 

50 

25 

Free  air,  cubic 

feet  per  minute. 

1 

m 
w 

36 
49 
68 

43 
56 
78 

•      54 
68 
94 

74 
94 
130 

These  figures  show  a  considerable  reduction  from  those  ob- 
tained with  the  brush  type  of  floor  renovator,  particularly  when 
the  larger  sizes  of  hose  are  used,  and  considerable  reduction 
can  be  made  in  the  capacity  of  the  exhauster  and  still  obtain 
the  best  results  when  using  carpet  renovator  and  bare  floor 
renovator  simultaneously. 

The  horse  power  at  the  hose  cock  required  to  operate  these 
felt-faced  floor  renovators  with  different  sizes  and  lengths  of 
hose  are: 

TABLE  15. 

HORSE  POWER  REQUIRED  AT  HOSE  COCK  TO  OPERATE  FELT-COVERED  FLOOR 
RENOVATORS  IN  CONJUNCTION  WITH  TYPE  A  RENOVATORS. 


Size  of  Hose, 
In.  Diameter. 

Length, 

in  Feet. 

100 

75 

50 

25 

Horse  power 

at  hose  cock. 

1 
V/4 

v/2 

1.0 
0.72 
0.79 

1.19 
0.83 
0.93 

1.49 
1.0 
1.13 

2.05 
1.39 
1.56 

In  this  case,  the  1^4 -in.  hose  is  the  most  economical  size  to 
use,  as  was  the  case  with  the  brush  renovators.  However,  the 
advantage  over  the  lJ/2-in.  hose  is  not  as  great  as  with  the  brush 
renovator. 

With  this  type  of  renovator,  the  manufacturer  has  some 
control  over  the  length  of  hose  which  the  operator  will  use  in 
connection  with  the  bare  floor  renovator,  as  he  may  open  the 
ends  of  the  renovator  just  sufficiently  to  produce  2  in.  of 
vacuum  under  same  with,  say,  50  ft.  of  hose.  Then,  if  the 


HOSE  97 

operator  should  attempt  to  use  the  renovator  with  25  ft.  of  hose, 
it  will  stick  and  push  hard  and  he  will  soon  learn  that  a  longer 
hose  is  necessary. 

Conditions  for  Plant  of  Small  Power. — For  locations  where 
it  is  desirable  to  sacrifice  efficiency  somewhat  to  reduction  in 
the  amount  of  power  required,  as  in  residences,  the  Type  A 
carpet  renovator  may  be  used  and  the  vacuum  under  the  same 
reduced  to  2  in.  mercury,  which  will  still  do  effective  cleaning, 
but  at  a  slower  rate,  as  was  shown  by  tests  in  Chapter  III. 
This  requires  not  exceeding  20  cu.  ft.  of  free  air  per  minute. 

With  this  quantity  of  air  the  velocity  in  the  hose  must  be 
considered  as,  in  order  to  have  a  clean  hose  at  all  times,  it  is 
necessary  to  maintain  a  velocity  in  the  hose  of  not  less  than 
40  ft.  per  second.  Referring  to  the  diagram,  Fig.  48,  it  will 
be  seen  that  this  velocity  will  not  be  obtained  in  any  hose 
larger  than  1J4  in-  and  this  is,  therefore,  the  largest  size  which 
can  be  used.  In  all  the  former  cases  the  velocity  was  so  much 
in  excess  of  this  minimum  that  its  consideration  was  not  nec- 
essary. 

With  a  vacuum  of  2  in.  of  mercury  in  the  renovator  and 
20  cu.  ft.  of  air  passing,  the  vacuum  at  the  hose  cock  will  be: 

TABLE  16. 
VACUUM   AT  HOSE  COCK,  WITH  2-iN.   VACUUM   AT  TYPE  A  RENOVATOR. 


Size  of  Hose. 
In.  Diameter 

Length,  in  Feet. 

100 

75                   50 

25 

Vacuum  at  hose  cock,  in.  hg. 

1 

154 

4 
2.6 

3.5                  3 
2.45                 2.3 

2.5 
2.15 

In  this  case  the  increase  in  vacuum  at  the  renovator  would 
not  be  objectionable  as,  with  4  in.  vacuum  at  the  hose  cock,  the 
vacuum  at  the  renovator  would  never  reach  the  standard  used 
with  the  former  deductions  and  the  volume  of  air  passing  could, 
therefore,  never  reach  29  cu.  ft.  Any  increase,  due  to  the  use 
of  shorter  hose,  would,  therefore,  be  an  advantage  in  its  ap- 
proach toward  the  standard  set  for  the  larger  plants.  There- 
fore, we  will  assume  that  a  vacuum  of  4  in.  mercury  will  be 


98  VACUUM    CLEANING    SYSTEMS 

maintained  at  the  hose  cock  with  1-in.  hose  and  a  vacuum  of 
2y2  in.  at  the  hose  cock  with  I^-m.  hose. 

The  renovators  for  bare  floor  work  will  be  the  felt-covered 
type  and  will  be  opened  at  the  ends  just  sufficiently  to  limit  the 
vacuum  within  the  same  to  2  in.  mercury  when  operating  with 
25  ft.  of  hose.  This  will  require  the  passage  of  40  cu.  ft.  of  free 
air  per  minute  when  1-in.  hose  is  used  and  35  cu.  ft.  when 
1*4 -in.  hose  is  used.  The  horse  power  at  the  hose  cock  will  be 
0.39  H.  P.  with  the  1-in.  diameter  hose  and  0.17  H.  P.  with  the 
l*4-in.  hose.  Here  again  we  see  that  the  1^4 -in-  hose  is  the 
more  economical  to  use. 

If  bristle  brushes  are  used  with  this  system  at  the  same  time 
that  carpet  renovators  are  in  use,  the  quantity  of  air  which 
will  have  to  pass  them,  in  order  to  maintain  the  vacuum  on  the 
system  at  the  proper  point  to  do  effective  cleaning  with  the 
carpet  renovators,  will  be: 

TABLE  17. 

AIR  QUANTITIES  WHEN   BRISTLE   BARE  FLOOR  RENOVATORS  ARE  USED  IN 
CONJUNCTION  WITH  TYPE  A  CARPET  RENOVATORS  AT  2  IN.  HG. 


Size  of  Hose, 
In.  Diameter. 

Length  of  Hose,  in  Feet. 

100 

75                   50 

25 

Free  air,  cu.  ft.  per  minute. 

1                              30 
154                          41 

36                   42 
48                   60 

60 
80 

The  use  of  these  brushes  in  plants  of  more  than  one-sweeper 
capacity  would  require  the  use  of  an  exhauster  of  greater 
capacity  than  is  required  for  either  the  carpet  or  the  bare 
floor  renovator.  Where  the  plant  is  of  but  one-sweeper  capacity, 
the  quantity  of  air  that 'would  pass  these  brushes,  were  the 
plant  of  proper  capacity  to  serve  the  carpet  and  floor  reno- 
vators, would  not  be  sufficient  to  do  effective  work,  as  was  ex- 
plained in  Chapter  IV.  In  such  cases,  this  arrangement  should 
.  be  prohibited. 

A  system  of  the  type  just  described  is  what  has  been  termed 
by  the  author  as  a  "small  volume"  plant  in  Chapter  IV. 


HOSE  99 

Limit  of  Length  for  Hose. — The  author  has  made  the  de- 
ductions in  this  chapter,  using  100  ft.  of  hose  as  the  maximum 
length.  This  is  considered  to  be  the  greatest  length  that  should 
be  used.  The  adoption  of  a  shorter  length  is  recommended  by 
many  manufacturers,  but  the  author  does  not  consider  that  the 
advantage  to  be  obtained  by  the  adoption  of  a  shorter  length 
justifies  the  additional  expense  of  piping  which  will  result  in 
many  cases.  This  will  be  governed  by  the  character  of  the 
building  and,  in  many  cases,  it  will  be  possible  to  use  50  ft.  as 
a  maximum.  It  has  been  the  practice  of  the  author  to  lay  out 
his  installations  so  that  any  point  on  the  floor  of  any  room  may 
be  reached  in  the  most  direct  line  with  75  ft.  of  hose.  When 
this  is  done  100  ft.  of  hose  will  easily  clean  any  part  of  the 
walls  or  ceilings  and  give  an  ample  allowance  for  running 
around  furniture  or  other  obstructions. 

The  figures  in  this  chapter  will  demonstrate  to  the  reader  the 
part  that  the  cleaning  hose  plays  as  a  limiting  factor  in  the 
operation  of  a  vacuum  cleaning  system  and  shows  the  care 
that  must  be  exercised  in  the  selection  of  the  proper  hose  for 
each  condition. 


CHAPTER  VII. 
PIPE  AND  FITTINGS. 

As  we  continue  to  follow  the  dust-laden  air  in  its  passage 
toward  the  vacuum  producer  we  next  encounter  that  portion  of 
the  conduit  which  is  permanently  and  rigidly  fixed  in  place 
in  the  building;  namely,  the  pipe  line,  its  fittings  and  other 
appliances. 

Hose  Inlets. — The  first  portion  of  this  conduit  which  we 
must  consider  is  the  point  where  the  hose  is  attached  to  the 
pipe  line ;  that  is,  the  inlet,  or,  as  it  is  often  improperly  termed, 
the  "outlet"  valves. 

As  it  is  necessary  to  close  the  inlets  air  tight  when  they  are 
not  in  actual  use,  in  order  to  prevent  the  entrance  of  air  except 
through  the  hose  lines  in  use,  some  kind  of  a  cut-off  valve  must 
be  provided,  as  well  as  a  receptacle  into  which  the  end  of  the 
hose  may  be  connected  when  desired. 

With  the  earlier  systems  a  high  degree  of  vacuum  was  carried 
in  the  pipe  lines  and  the  vacuum  producers  were  of  small  dis- 
placement. Slight  leakage  would  greatly  reduce  the  capacity 
of  the  system  and  the  best  form  of  valve  was  necessary.  The 
valve  adopted  was  the  ordinary  ground-seat  plug  cock,  on  ac- 
count of  its  unobstructed  air  passage  and  air-tight  closing.  The 
hose  was  connected  to  these  cocks  either  by  a  ground-joint, 
screwed  coupling  or  by  a  slip  coupling  similar  to  those  used  to 
unite  the  sections  of  the  cleaning  hose.  An  inlet  cock  of  this 
type  is  illustrated  in  Fig.  51. 

These  cocks  projected  about  4^  in.  beyond  the  face  of  the 
finished  wall  and  formed  a  considerable  obstruction,  especially 
when  located  in  halls  or  corridors.  In  order  to  reduce  the  pro- 
jection into  the  apartment  the  manufacturers  of  the  systems 
using  screwed-hose  couplings  and  substituted  a  projecting 
nipple  closed  by  a  cap  screwed  in  place.  The  whole  projected 
only  y^  in.  beyond  the  finished  wall  line. 

100 


PIPE  AND  FITTINGS 


101 


These  outlets  were  suitable  for  use  only  with  hose  having 
screwed  connections.  When  an  attempt  is  made  to  remove 
the  cap  with  the  vacuum  producer  in  operation,  there  is  a  ten- 
dency for  the  vacuum  to  cause  the  cap  to  hug  the  last  thread 
and  render  its  removal  difficult.  Also,  when  the  suction  is 
finally  broken  it  is  accomplished  with  considerable  hissing 
noise. 

In  order  to  permit  the  use  of  the  slip  type  of  hose  coupling, 
a  hinged  flap  valve  was  substituted  for  the  screwed  cap,  a  rub- 
ber gasket  being  placed  under  the  cap.  This  was  held  firmly 
in  place  by  the  vacuum  in  the  pipe  line.  The  interior  of  the 
casting  inside  of  the  flap  was  turned  to  a  slip  fit  for  the  end 
of  the  hose  coupling.  With  this  type  of  valve  and  the  slip  hose 
coupling,  described  in  Chapter  VI,  it  is  possible  to  reverse  the 
hose  to  equalize  wear  and  remove  obstructions. 

These  inlets  have  been  made  with  valves  that  are  closed 
only  by  gravity  when  there  is  no  vacuum  on  the  system  and 
many  are  so  constructed  that  when  opened  wide  they  will  re- 
main open  with  the  vacuum  on  the  piping.  This  type  of  valve 


FIG.   51.      INLET   COCK  TO  PREVENT   AIR   LEAKAGE   WHEN   NOT 

IN  USE. 

will  often  be  opened  by  the  inquisitive  person  when  no  vacuum 
exists  in  the  system  and  as  there  are  no  immediate  results, 
they  may  be  left  open  with  the  result  that  there  will  be  a  very 
large  leakage  of  air  on  starting  the  vacuum  producer.  This 
makes  it  necessary  for  some  one  to  make  a  tour  of  the  building 
in  order  to  close  the  valve  which  is  open  before  the  system  can 
be  efficiently  operated.  If  the  vacuum  producer  is  designed 
to  operate  several  renovators  simultaneously,  it  may  not  be 
discovered  that  there  are  any  valves  open  and  a  considerable 
amount  of  power  will  be  wasted. 


102 


VACUUM    CLEANING    SYSTEMS 


In  order  to  overcome  this  difficulty  it  is  necessary  to  provide 
a  spring  on  the  hinge  of  the  flap  valve  that  will  automatically 
close  the  valve  whenever  the  hose  is  withdrawn.  When  the 
inlets  are  located  in  public  places  they  should  be  fitted  with  a 
lock  attachment  to  prevent  them  from  being  opened  by  unau- 
thorized persons. 

A  valve  of  this  type  is  illustrated  in  Fig.  52.  This  valve 
has  a  projection  on  its  inner  face  which  engages  with  a  ridge 
on  the  hose  couplings,  preventing  the  removal  of  the  hose  with- 
out slightly  raising  the  cap  and  making  it  impossible  to  acci- 
dently  pull  the  hose  out  of  the  inlet. 


FIG.    52.      TYPE    OF   AUTOMATIC    SELF-CLOSING    INLET    COCK. 

The  particular  valve  here  shown  is  suitable  for  use  only  with 
the  all-rubber  hose  connection  described  in  Chapter  VI. 

We  must  next  consider  the  material  of  which  the  conduit 
itself  is  to  be  made.  The  commercial  wrought-iron  or  mild 
steel,  screw- jointed  pipe,  such  as  is  used  for  water  and  steam 
lines,  is  probably  the  best  suited  for  this  purpose  and  was  the 
first  material  used.  In  earlier  installations  the  pipe  was  gal- 
vanized, but,  owing  to  the  tendency  for  the  zinc  coating  to 
form  irregularities  within  the  pipe,  its  use  has  been  aban- 
doned in  favor  of  the  commercial  black  iron  pipe. 

Seamless  drawn  tubing  would  undoubtedly  make  the  ideal 
material  for  this  purpose.  However,  the  ordinary  butt  or  lap- 
welded  pipe  is  satisfactory  and  is  now  generally  used. 

Sheet  metal  pipe  was  introduced  by  one  manufacturer  but 
its  use  was  shortly  abandoned  in  favor  of  the  commercial  pipe. 


PIPE  AND  FITTINGS  103 

As  joints  and  changes  in  direction  are  necessary  in  the  pipe 
lines,  some  sort  of  fittings  must  be  used.  The  ideal  conduit  for 
passage  of  dust-laden  air  should  be  of  uniform  bore  and  as 
smooth  on  the  inside  as  a  gun  barrel.  Various  attempts  have 
been  made  to  accomplish  this  result  in  commercial  installations, 
one  of  which  is  illustrated  in  Fig.  53.  These  fittings  are  made 
up  of  three  parts  for  a  coupling  and  four  for  a  branch  or 
change  in  direction.  One  of  these  is  screwed  on  to  the  end  of 
each  piece  of  pipe,  the  pipe  butting  against  a  shoulder  and  the 
end  of  the  pipe  made  to  register  with  the  bore  of  the  fitting  by 
reaming.  This  piece  is  faced  true  and  fitted  against  the  face 
of  the  casting,  forming  the  bend  or  branch,  or  fitted  against 
the  piece  on  the  end  of  the  other  length  of  pipe.  A  thin  gasket 
is  placed  between  them,  a  projecting  ring  on  one  piece  fitting 


FIG.  53.   "SMOOTH  BORE"  PIPE  COUPLING. 

into  a  groove  on  the  other,  causing  the  bore  of  the  two  halves 
to  register.  The  two  halves  are  joined  together  by  the 
V-grooved  clamp,  held  in  place  by  a  small  bolt.  This  is  theo- 
retically an  ideal  joint,  but  the  clamp  is  not  of  sufficient 
strength  to  withstand  the  strain  of  settlement  of  the  building 
and  breakages  are  frequent.  Several  instances  of  this  character, 
particularly  on  steamers,  have  come  to  the  observation  of  the 
author,  and  there  are  several  buildings  which  have  been  roughed 
in  with  this  type  of  fitting,  used  on  concealed  piping,  which  were 
found  to  be  useless  on  the  completion  of  the  building,  due  to 
breaking  of  the  joints  in  inaccessible  places. 

A  modification  of  this  joint  which  will  have  ample  strength 
can  be  made  by  using  standard  pipe  flanges,  screwing  the  pipe 


104 


VACUUM    CLEANING    SYSTEMS 


through  the  flange  and  facing  the  end  off  in  a  lathe.  Fittings 
could  be  made  with  a  bore  equal  to  that  of  the  pipe  and  proper 
alignment  secured  by  the  use  of  dowel  pins,  as  illustrated  in 
Fig.  54.  The  cost  of  making  this  joint  would  be  high  and  they 
would  occupy  too  much  space  to  be  easily  concealed  in  par- 
titions, furring  or  other  channels  usually  provided  for  the 
reception  of  such  piping. 

The  standard  Durham  recessed  drainage  fitting,  having  the 
inside  cored  to  the  bore  of  the  pipe  and  recesses  provided  for 
the  threads  as  used  in  connection  with  the  modern  plumbing 
system,  if  left  ungalvanized  and  having  the  inside  well  sand- 
blasted to  remove  all  rough  places,  makes  a  serviceable  fitting. 
Care  should  be  exercised  to  cut  the  threads  on  the  piping  of 


PIG.    54.      JOINT    MADE    OF    STANDARD    PIPE    FLANGES. 

proper  depth  to  allow  the  end  of  the  pipe  to  come  as  close  to 
the  shoulder  of  the  recess  as  practicable  and  to  obtain  a  tight 
joint.  The  end  of  the  pipe  should  be  carefully  reamed  before 
assembling. 

These  fittings  have  become  standard  with  nearly  all  manu- 
facturers and  are  illustrated  in  Fig.  55,  which  shows  the  right 
and  wrong  way  to  install  same. 

Trouble  was  experienced  on  some  of  the  earlier  systems  using 
high  vacuum  with  the  fittings  cutting  out  on  the  side  sub- 
jected to  the  impact  of  the  dust-laden  air.  To  overcome  this 
trouble  one  manufacturer  re-inforced  the  fittings  by  increasing 
the  thickness  of  metal  at  the  point  affected.  The  trouble  was 
undoubtedly  caused  by  too  high  a  velocity  in  the  pipe  line,  as 
in  the  case  of  the  small  brass  stems,  explained  in  Chapter  V. 
With  the  introduction  of  vacuum  control  and  larger  pipes, 


PIPE   AND  FITTINGS 


105 


this  trouble  disappeared  and    the  special  fittings  never  came 
into  general  use. 

While  the  utmost  care  should  be  taken  to  prevent  stoppage 
of  the  pipe  lines  these  stoppages  are  likely  to  occur  in  the  best- 

RIGHT  WAY.  WRONG  WAY. 


To  Cleaner 


To  Cleaner 


To  Cleaner 


Use  two  Y- branches  instead  of  straight  or  dean  out  tees.  Incase  the  latter  are  used 
the  dirt  will  shoot  by  into  the  other  branch. 


To  Cleaner 


To  Cleaner 


Always  place  Y- branches  so  they  will  turn  in  the  direction  of  the  flow. 


To  Cleaner 


To  Cleaner 


Place  t-he  clean-out  at  right  angles  to  the  direction  of  flow  entering  the 
-fitting.  Otherwise  It  serves  as  a  pocket  to  catch  passing  dirt. 


To  Cleaner 


Riser 


To  Cleaner 


Riser 


Drop 

Special  care  must  be  exercised  io  see  that  there  is  no  opportunity  ibrd/rt  fa  collect  in  the 
basement  drops.  Above  is  shown  a  common  wrong  way  and  two  possible  right  ways. 


FIG.    55.      STANDARD    DURHAM   RECESSED    DRAINAGE    FITTINGS 
GENERALLY  USED  IN  VACUUM  CLEANING  INSTALLATIONS 


106 


VACUUM    CLEANING    SYSTEMS 


constructed  lines  and  ample  clean-out  plugs  should  be  provided 
for  the  removal  of  such  stoppage.  Brass  plugs  are  the  most 
serviceable  for  this  purpose,  as  they  are  easily  removed  when 
necessary  and  can  usually  be  replaced  air  tight. 

The  brass  clean-outs,  while  most  satisfactory,  are  costly  when 
installed  in  large  sizes.  Equally  satisfactory  results  can  be  ob- 
tained at  a  lower  cost  by  using  2-in  diameter  plugs  on  all  lines 
2  in.  and  over  in  diameter. 


1000 


Velocity  in  Pipe,  Ft.  per  Sec. 

50        60        70     80    90    100 


Length  of  Pipe.  Feet 
)400    300      200    150 


500400    300 


100 


1  ^  3  5         7         10         15     20 

Average  Vacuum  in  Pipe,  In.  Mercury 

FIG.    56.      FRICTION    LOSS    IN   PIPE    LINES. 

•4 

Matches  are  perhaps  the  most  frequent  cause  of  stoppage  in 
pipe  lines.  Stoppage  from  this  cause  can  be  largely  avoided 
by  the  use  of  pipe  of  sufficient  size  to  permit  the  match  to  turn 
a  complete  somersault  within  the  pipe  whenever  it  catches 
against  a  slight  obstruction  or  rough  place  in  the  pipe  or 


t 
PIPE  AND  FITTINGS  107 

fittings.  A  2-in.  diameter  pipe  is  just  large  enough  to  permit 
this  and  smaller  sizes  of  pipe  should  be  avoided  whenever 
possible. 

Pipe  Friction. —  The  friction  loss  in  piping  follows  the  same 
law  as  that  in  hose  lines  and  is  easily  computed  by  use  of  the 
chart  (Fig.  56),  which  is  constructed  on  the  same  general 
principle  as  the  chart  of  hose  friction  (Fig.  48).  The  directions 
for  use  of  the  hose  chart  apply  to  the  pipe  chart.  In  computing 
this  chart  the  actual  inside  diameter  of  the  commercial  wrought- 
iron  pipes  have  been  used  instead  of  the  nominal  diameters, 
resulting  in  an  increased  capacity  for  all  sizes  except  2^-in. 
which  is  less  than  the  nominal  diameter. 

Determination  of  Proper*  Size  Pipe. — Friction  in  the  pipe 
lines  tends  to  increase  the  vacuum  to  be  maintained  and  there- 
fore the  power  to  be  expended  at  the  vacuum  producer  and 
should  be  kept  as  low  as  possible.  The  pipe  sizes  should  be 
made  as  -large  as  conditions  will  permit.  The  limit  of  size  is 
fixed  by  the  velocity  in  the  pipe.  When  it  is  necessary  to  lift 
the  dirt  to  any  extent,  the  velocity  should  mot  be  allowed  to 
fall  below  40  ft.  per  second  at  any  time.  When  the  pipe  is  a 
vertical  drop,  the  velocity  does  not  matter  as  gravitation  will 
assist  the  air  current  in  removing  the  dirt.  When  the  line  is 
horizontal  a  lower  velocity  than  40  ft.  per  second  is  permissible 
at  times,  provided  that  this  minimum  velocity  is  exceeded  at 
frequent  intervals  to  flush  out  any  dirt  that  has  lodged  in  the 
pipe  during  periods  of  low  velocity. 

If  a  Type  A  renovator  is  used  with  1-in.  hose  and  a  vacuum 
of  10  in.  of  mercury  maintained  at  the  hose  cock,  the  minimum 
air  passing,  with  100  ft.  of  hose  in  use,  will  be  29  cu.  ft.  of  free 
air  per  minute,  which  is  equivalent  to  44  cu.  ft.  at  10  in.  of 
vacuum.  The  entering  velocity  in  the  pipe  should  be  calculated 
with  air  at  this  density.  This  will  give  a  velocity  of  50  ft. 
per  second  in  a  lj^-in.  pipe,  but  only  30  ft.  per  second  in  a  2-in. 
pipe.  Therefore,  the  1^-in.  pipe  is  the  largest  that  should  be 
used  where  lifts  occur  on  a  line  serving  but  one  Type  A  reno- 
vator with  1-in  hose.  When  the  renovator  is  tilted  at  a  con- 
siderable angle  or  lifted  from  the  carpet,  as  will  frequently 
occur  in  cleaning  operations,  the  quantity  of  air  passing  the 
renovator  will  be  upwards  of  42  cu.  ft.  of  free  air,  equivalent 


108  VACUUM    CLEANING    SYSTEMS 

to  62  cu.  ft.  at  10-in.  vacuum.  When  this  occurs  the  velocity 
in  a  2-in.  pipe  will  be  44  ft.  per  second,  which  will  be  ample  to 
flush  a  'horizontal  line  of  piping. 

If  1^4-in  hose  is  used  with  a  Type  A  renovator,  the  minimum 
quantity  of  air  will  be  29  cu.  ft.  and  the  vacuum  entering  the 
pipe  will  be  6  in.  mercury,  giving  an  equivalent  volume  of  37 
cu.  ft.  This  will  produce  a  velocity  of  42  ft.  per  second  in  a 
\y2 -in.  pipe,  which  is  the  largest  that  can  be  used  where  a  lift 
occurs.  However,  when  the  renovator  is  lifted  free  of  the 
carpet,  the  air  quantity  will  be  62  cu.  ft.  of  free  air,  equivalent 
to  80  cu.  ft.  at  6  in.  of  vacuum,  and  will  produce  a  velocity 
of  39  ft.  per  second  in  a  2^2 -in.  pipe.  This  would  be  just  about 
sufficient  to  flush  a  horizontal  line. 

If  1^-in.  hose  were  used  the  air  quantity  will  be  29  cu.  ft. 
and  the  vacuum  entering  the  pipe  5  in.  mercury,  equiva- 
lent to  35  cu.  ft.  This  will  give  a  velocity  in  a  1^2 -in.  pipe  of 
40  ft.  per  second.  When  the  renovator  is  raised  from  the  car- 
pet, the  air  quantity  will  be  upwards  of  90  cu.  ft.  of  free  air, 
equivalent  to  110  cu.  ft.  at  the  density  of  that  entering  the  pipe, 
and  will  produce  a  velocity  of  33  ft.  per  second  in  a  3-in.  pipe. 
This  is  too  low  to  thoroughly  flush  a  horizontal  pipe. 

The  figures  given  above  are  repeated  from  Chapter  VI  and 
show  that  the  use  of  1%-iu.  instead  of  1-in.  hose,  permits  the 
use  of  a  larger-sized  horizontal  pipe  line  for  serving  one  reno- 
vator, but  that  the  use  of  1^-in.  hose,  instead  of  1^-in.,  will 
not  permit  of  any  enlargement  in  the  pipe  size.  Since  we  have 
seen  in  Chapter  VI  that  a  1^4 -in.  hose  gives  the  least  expen- 
diture of  power  when  used  with  a  Type  A  renovator,  there 
will  be  no  gain  from  a  reduction  in  the  pipe  friction  due  to 
the  adoption  of  this  hose. 

The  dependence  on  the  raising  of  the  renovator  from  the  floor 
to  flush  out  a  larger  pipe  line  should  not  be  carried  beyond  that 
to  be  obtained  from  a  single  renovator.  That  is,  when  the  pipe 
must  serve  more  than  one  renovator  at  the  same  time,  the  quan- 
tity of  air  that  two  or  more  renovators  will  pass,  if  they  were 
raised  from  the  floor  at  the  same  time,  should  not  be  used  in 
determining  the  limiting  velocity  in  the  pipe,  as  such  an  occur- 
rence is  not  likely  to  be  obtained  often  enough  to  thoroughly 
flush  the  pipe.  Furthermore,  there  will  be  times  when  this  pipe 
will  have  to  serve  only  one  renovator  and  the  pipe  will  not  be 


PIPE   AND  FITTINGS 


109 


adequately  flushed.  When  the  pipe  is  serving  more  than  one 
renovator,  the  actual  air  passing  the  renovators  should  be  used 
in  determining  the  maximum  size  of  pipe  and  it  is  advisable  to 
use  this  maximum  size  in  nearly  all  cases  where  the  structural 
conditions  will  permit. 
These  sizes  will  then  be: 

TABLE  18. 
PIPE  SIZES  REQUIRED,  AS  DETERMINED  BY  AIR  PASSING  RENOVATORS. 


Number  of  Renovators  in   Use. 

Cu.  Ft. 
per  min. 

Pipe  Sizes,  In.  Diam. 

With  1-in. 
Hose. 

With  1/i-in. 
Hose. 

1 
2 
3 
4 
5 
6 

29 
58 
87 
116 
145 
174 

2 

2^ 
3 

3/2 

3^ 
4 

2/ 

2/2 

3 
3H 

3/2 

4 

Using  these  maximum  sizes,  the  friction  loss  in  a  pipe  line, 
with  carpet  renovators  in  use  exclusively,  will  be: 

TABLE  19. 

FRICTION  Loss  IN  PIPE  LINES,  WITH  CARPET  RENOVATORS  IN  USE 
EXCLUSIVELY. 


Number  of  Sweepers. 


Friction  Loss  per  100  Feet,  Inches. 


With  1-in.  hose. 


With  \l/4-\n.  hose. 


0.20 
0.30 
0.24 
0.19 
0.30 
0.24 


0.06 
0.20 
0.17 
0.13 
0.22 
0.17 


These  friction  losses  are  figured  with  a  density  of  air  in  the 
pipe  equal  to  6-in.  vacuum  in  case  of  the  1^4 -in.  hose  and  10-in. 
vacuum  in  case  of  the  1-in.  hose,  which  will  be  the  density  of 
the  air  entering  the  pipe,  while  the  average  density  should  be 
used  in  order  to  give  correct  results.  If  the  pipe  line  is  not 
over  400  ft.  equivalent  length  the  results  will  be  approximately 
correct. 

These  results  show,  first,  that  the  friction  loss  in  pipe  lines 
is  much  lower  than  that  in  the  hose  lines  used  with  the  same 
system;  second,  that  the  higher  vacuum  in  the  pipe  causes 
greater  loss,  an  argument  in  favor  of  the  use  of  larger  hose. 


110  VACUUM    CLEANING1  SYSTEMS 

These  friction  losses  are  obtained  only  when  carpet  reno- 
vators are  used  exclusively  and  all  the  renovators  are  held  in 
the  proper  position  to  perform  the  most  economical  cleaning. 
In  actual  practice  this  condition  will  not  exist  except  when  one 
renovator  is  used.  Where  more  than  one  renovator  is  in  use 
simultaneously,  some  of  the  renovators  will  be  raised  from  the 
floors  at  the  time  others  are  in  position  to  do  effective  cleaning 

WO' 2' Pie         *          ZOO'tfPif* 


SZ'Vac 


ZOO'-l'Pirx         B         HOP  -li'  Pit* 


Q<*&f?ac 

*&'' 
€•/ 


ll'Vac 


ZOO'^'Pfpe          B         ZOO'-li'pipe  C 

Vac.  .^&J<3"Vac.  //"Vac 


Brush  "6" 

75  Cu.  Ft  Carpet  Reno  voter  "a 

ZSCu.Pt 


Brush 

Carpetfonovator  85Cu.Ft 

Z"Yac.Z3Cu.Ft. 


t  A          lOO'-li"  Pipe          9         200LliPipe  f 

V^  4fVac  !y&J<l5Vac. 6. 5  Vac 


^ 

Carpet  Renovator  Brush  120  Cu.  Ft. 

5J"Vac  Z4.Cu.ft 

FIGS.    57-60.      DIAGRAMS   SHOWING  OPERATION  OF   BRUSH  AND 
CARPET   RENOVATORS    UNDER   DIFFERENT   CONDITIONS. 

and  will  admit  a  greater  quantity  of  air,  increasing  the  friction. 
This  is  not  a  serious  condition  as  the  time  that  the  renovators 
will  be  raised  is  only  a  small  part  of  the  total  time  spent  in 
cleaning  and  will  merely  reduce  the  efficiency  of  the  other 
renovators  temporarily.  However,  when  brushes  or  floor  reno- 
vators are  used  at  the  same  time  as  the  carpet  renovators,  there 
will  be  a  continuous  flow  of  air  in  greater  quantities  through 


t 
PIPE  AND  FITTINGS  111 

these  brushes,  which  will  permanently  increase  the  friction  loss. 
The  use  of  a  single  brush  or  floor  renovator  with  the  same  sized 
pipe  as  is  necessary  to  operate  the  carpet  renovator  will  not 
reduce  the  efficiency  of  the  brush,  as  a  high  degree  of  vacuum 
at  the  brush  or  floor  renovator  is  not  necessary  or  even  per- 
missible and  a  further  slight  reduction  will  not  affect  the  oper- 
ation of  these  renovators. 

When  a  brush  or  floor  renovator  is  used  on  the  furthest  out- 
let from  the  vacuum  producer  at  the  same  time  that  carpet 
renovators  are  being  used  on  outlets  nearer  the  vacuum  pro- 
ducer, the  larger  quantity  of  air  passing  the  brush  'will  tend  to 
reduce  the  vacuum  at  the  hose  cock  to  which  the  carpet  reno- 
vator is  attached  and  thereby  impair  its  efficiency.  For  ex- 
ample, if  we  have  a  brush  renovator  connected  through  100  ft. 
of  1-in.  hose  to  an  outlet  at  the  end  of  a  pipe  line  400  ft.  long, 
properly  designed  to  serve  two  carpet  renovators,  the  vacuum 
at  the  separators  should  be  maintained  at  10-in.,  plus  2X0.20 
plus  2X0.30,  or  11  in.  of  mercury.  Suppose  that  this  vacuum 
is  automatically  maintained  at  this  point  and  a  carpet  reno- 
vator be  attached  200  ft.  from  end  of  pipe  (Fig.  57).  The 
quantity  of  air  passing  through  the  2^ -in.  pipe  B-C  will  be 
approximately  29  plus  40  or  69  cu.  ft.,  and  the  friction  loss  in 
this  pipe  will  be  1.1  in.  The  vacuum  maintained  at  the  outlet 
B  (Fig.  57)  will  be  9.9  in.  or  approximately  the  correct  vacuum 
to  maintain  4^ -in.  vacuum  at  the  renovator  "a."  The  friction 
loss  in  the  pipe  line  from  B  to  A  will  be  0.7  in.  and  the  re- 
sulting vacuum  at  the  hose  cock  A  will  be  9.2  in.  The  quantity 
of  air  passing  the  brush  will  be  40  cu.  ft.  Under  these  con- 
ditions there  will  be  no  loss  in  efficiency  of  cleaning  due  to  the 
brush  renovator  being  used  on  the  end  of  the  line.  If  the 
operator  using  the  brush  at  the  outlet  A  should  use  only  25 
ft.  of  hose  instead  of  100  ft.  (Fig.  58)  the  air  passing  this 
brush  will  be  75  cu.  ft.  and  the  vacuum  at  the  hose  cock  A 
will  be  6.8  in.  The  vacuum  at  the  hose  cock  B  will  be  8.8  in. 
and  the  vacuum  at  the  carpet  renovator  "a"  will  be  reduced 
to  3^2  in.  with  25  cu.  ft.  of  air  passing,  which  will  reduce 
the  efficiency  of  the  carpet  renovator  "a." 

If  the  brush  renovator  be  attached  to  the  hose  cock  B  (Fig. 
59),  using  25  ft.  of  hose,  the  vacuum  at  hose  cock  B  will  be 


112  VACUUM  CLEANING  SYSTEMS 

• 

9  in.  and  the  brush  renovator  will  pass  85  cu.  ft.  of  air,  while 
the  vacuum  at  hose  cock  A  will  now  be  reduced  to  8.6  in.  and 
the  vacuum  at  the  renovator  will  be  reduced  to  3  in.  mercury 
and  the  air  passing  to  23  cu.  ft. 

If  a  brush  type  of  renovator  be  used  at  each  outlet,  with  25 
ft.  of  hose  in  each  case  and  the  vacuum  at  the  separator  be 
maintained  at  11  in.  mercury  the  vacuum  at  hose  cock  B  will 
be  7  in.  and  brush  "a"  will  pass  76  cu.  ft.  of  air  while  the 
vacuum  at  hose  cock  "a"  will  be  5  in.  and  brush  "b"  will 
pass  63  cu.  ft.  of  air  or  a  total  of  144  cu.  ft.,  which  will  be 
in  excess  of  the  70  cu.  ft.  per  renovator,  recommended  as  the 
capacity  of  the  plant  in  Chapter  VI.  This  will  not  result  in 
any  loss  of  efficiency  if  the  vacuum  producer  be  designed  to 
handle  but  140  cu.  ft.  as  a  maximum,  for  the  vacuum  at  the 
separator  will  then  fall  to  a  point  where  but  140  cu.  ft.  passes, 
resulting  in  a  decrease  in  the  vacuum  throughout  the  system. 
But  as  only  brushes  are  now  in  use  there  will  be  no  loss  in 
efficiency,  owing  to  the  reduction  in  the  vacuum  at  the  brushes. 

When  1*4 -in.  hose  is  used  with  a  carpet  renovator  at  the  end 
of  the  pipe  line  connected  through  100  ft.  of  hose  and  a  brush 
at  the  hose  cock  B  connected  through  25  ft.  of  hose  (Fig.  60), 
the  worst  case  of  the  three  already  cited,  the  vacuum  at  the 
separator  being  maintained  at  that  necessary  to  carry  4^  in. 
when  two  carpet  renovators  are  in  use,  the  vacuum  at  the  hose 
cock  B  will  be  4.5  in.  and  brush  "a"  will  pass  116  cu.  ft.  of 
air  while  the  vacuum  at  hose  cock  A  will  be  4.4  in.  and  the 
vacuum  in  renovator  "b"  will  be  3.7  in  and  will  pass  24 
cu.  ft.  of  air. 

These  are  better  cleaning  conditions  than  were  obtained  when 
1-in  hose  was  used.  It  will  be  noted  that  the  total  air  passing 
the  exhauster  is  now  140  cu.  ft.  and  this  must  not  be  reduced 
or  there  will  be  a  falling  off  in  the  vacuum  at  the  carpet  reno- 
vator "b."  It  is,  therefore,  necessary  for  the  exhauster  to  be 
capable  of  handling  140  cu.  ft.  of  air  or  70  cu.  ft.  of  air  per 
renovator  in  order  to  do  effective  carpet  cleaning  when  carpet 
renovators  and  brushes  are  used  in  conjunction. 

When  two  floor  brushes  are  used  with  the  above  arrange- 
ment of  pipe  and  hose,  the  vacuum  must  fall  considerably  or 


PIPE  AND  FITTINGS  113 

the  air  quantity  be  greatly  increased.  However,  the  reduction 
in  vacuum  will  not  result  in  serious  loss  in  efficiency  when  only 
brushes  are  in  use. 

When  a  larger  number  of  sweepers  are  used  with  a  system 
of  piping,  it  is  necessary  to  allow  70  cu.  ft.  of  free  air  per 
sweeper  in  figuring  the  sizes  of  pipe  to  be  used,  and  the  total 
loss  of  pressure  in  the  piping  between  the  outlet  farthest  from 
the  vacuum  producer  and  that  nearest  to  same  must  be  limited 
in  order  to  prevent  too  wide  a  difference  in  the  vacuum  at  the 
hose  cock  when  all  the  sweepers  for  which  the  plant  is  designed 
are  in  use.  The  author  considers  that  this  loss  in  pressure 
should  not  be  greater  than  2  in.  mercury  in  order  to  give  satis- 
factory results. 

Before  the  piping  system  can  be  laid  out  and  the  sizes  of 
piping  determined  it  is  necessary  to  ascertain,  first,  the  num- 
ber of  sweepers  to  be  operated  simultaneously  and  the  number 
of  risers  necessary  to  properly  serve  these  sweepers. 

Number  of  Sweepers  to  be  Operated. — This  is  determined 
by  the  character  of  the  surfaces  to  be  cleaned,  the  amount  of 
such  surface,  and  the  time  allowed  for  cleaning. 

It  has  been  demonstrated  in  actual  practice  that  one  operator 
can  clean  as  high  as  2,500  sq.  ft.  of  carpet  when  same  is  on 
floors  of  comparatively  large  areas,  and  not  over  1,500  sq.  ft. 
when  the  carpets  are  on  small  rooms;  2,000  sq.  ft.  is  considered 
to  be  a  fair  average. 

Bare  floors  are  cleaned  more  rapidly.  In  school  house  work 
an  ordinary  class  room  has  been  cleaned  in  10  minutes,  or  at 
the  rate  of  7,200  sq.  ft.  per  hour,  but  time  is  occupied  in  moving 
from  one  room  to  another  and  the  writer  considers  5,000  sq.  ft. 
per  hour  as  rapid  cleaning  and  3,500  sq.  ft.  as  a  fair  average. 

The  time  of  cleaning  will  vary  in  buildings  of  different  char- 
acter and  used  for  different  purposes.  In  office  buildings  the 
cleaning  force  work  throughout  the  night  or  about  10  hours, 
while  in  school  houses  the  cleaning  is  done  by  the  janitor  force 
which  has  been  on  duty  throughout  the  school  period  and  the 
time  is  necessarily  limited  to  about  two  or  three  hours  after 
school  hours,  the  corridors  and  play  rooms  being  cleaned  during 
the  school  period  and  only  the  class  rooms  being  cleaned  after- 
closing  time. 


114 


VACUUM    CLEANING    SYSTEMS 


Let  us  assume,  as  an  example,  an  office  building  having  eight 
floors  each  100  ft.  x  150  ft.,  with  a  floor  plan  as  shown  in 
Fig.  61. 

The  corridors,  stairs  and  elevator  halls  will  probably  be 
floored  with  marble  which  must  be  scrubbed  in  order  to  remove 
the  stain  accumulated  during  the  day  and  they  will  not  be  con- 
sidered in  connection  with  a  dry  vacuum  cleaning  system.  The 
area  of  the  floors  in  the  offices  on  any  floor  will  be  approximately 
10,000  sq.  ft.  and  one  floor  can  be  cleaned  by  one  operator  in 
5  hours,  or  two  floors  during  the  cleaning  period,  so  the  plant 
must  be  of  sufficient  size  to  serve  four  sweepers  simultaneously. 


FIG.    61.      TYPICAL   FLOOR    PLAN   OF   OFFICE    BUILDING    ILLUS- 
TRATING NUMBER  OF  SWEEPERS  REQUIRED. 

In  a  school  house  containing  four  class  rooms,  where  the 
janitor  cleans  the  play  rooms  and  corridors  during  the  school 
period,  as  can  be  readily  done  with  a  vacuum  cleaner  since 
there  will  be  no  dust  scattered  about  to  fill  the  air  and  render 
it  unsanitary,  the  class  rooms  can  easily  be  cleaned  in  one  hour 
by  one  operator.  The  author  considers  that  one  sweeper  capac- 
ity for  each  six  to  eight  rooms  is  ample  for  a  large  school. 


PIPE  AND  FITTINGS  .115 

Buildings  of  special  construction  and  used  for  special  pur- 
poses must  be  considered  differently  according  to  the  conditions 
to  be  met,  but  the  size  of  the  plant  can  be  readily  determined 
in  each  case  by  use  of  the  rules  already  given. 

Number  of  Risers  to  be  Installed. —  Much  difference  of 
opinion  exists  among  the  various  manufacturers  of  vacuum 
•cleaning  systems  as  to  the  maximum  length  of  hose  that  should 
be  used  with  a  cleaning  system,  and  as  this  maximum  length 
determines  the  number  of  risers  to  be  installed,  some  fixed 
standard  is  necessary.  As  already  stated  in  Chapter  VI,  the 
author  considers  that  this  maximum  should  be  fixed  at  75  ft. ; 
that  is,  the  risers  should  be  so  spaced  that  all  parts  of  the  floor 
of  the  building  can  be  reached  with  75  ft.  of  hose.  Where  50 
ft.  is  used  as  a  maximum,  as  is  recommended  by  many  manu- 
facturers, the  number  of  risers  would  be  increased,  incurring  a 
greater  cost  of  installation  and  requiring  the  operator  to  Shift 
his  hose  from  one  inlet  to  another  more  often  than  would  be 
the  case  where  fewer  inlets  were  used,  and  more  time  would 
be  required  in  cleaning,  with  a  slight  reduction  in  the  power. 
The  author  does  not  consider  that  this  reduction  in  power  would 
be  sufficient  to  offset  the  additional  time  required  to  change 
the  hose  from  one  inlet  to  another. 

The  best  and  quickest  way  to  determine  the  number  of  risers 
necessary  is  to  cut  a  piece  of  string  to  the  length  repre- 
senting 75  ft.  on  the  scale  of  the  plans,  and  by  running  this 
around  the  plan  using  corridor  doors  for  access  to  all  rooms, 
wherever  possible,  locate  the  riser  so  that  every  point  can  be 
reached  with  the  string.  In  the  case  of  the  building  illustrated 
in  Fig.  61  four  risers  located  as  shown  will  be  necessary. 

Size  of  Risers. — Before  we  can  determine  the  size  of  risers 
to  be  installed  it  is  necessary  to  determine  the  probable  num- 
ber of  sweepers  that  will  be  attached  to  any  one  riser  simul- 
taneously. In  the  case  of  the  building  (Fig.  61)  it  is  possible 
that  there  may  be  four  sweepers  attached  to  one  riser  and  it  is 
also  possible  that  there  may  be  but  one,  and  two  sweepers  to 
a  riser  is  considered  to  be  a  safe  assumption.  The  author  uses 
the  following  rule  in  determining  the  size  of  risers  to  use: 

Where  the  number  of  sweepers  is  double  the  number  of  risers, 
assume  that  all  sweepers  will  be  on  one  riser  simultaneously. 


116  VACUUM    CLEANING    SYSTEMS 

Where  the  number  of  sweepers  is  equal  to  the  number  of 
risers,  assume  that  half  the  sweepers  will  be  on  one  riser 
simultaneously. 

Where  the  number  of  sweepers  is  half  the  number  of  risers, 
assume  that  one-quarter  of  the  sweepers  will  be  on  one  riser 
simultaneously. 

When  no  lifts  occur  a  low  velocity  in  the  riser  is  not  objec- 
tionable and  the  size  of  the  riser  should  be  made  equal  to  the 
size  of  the  horizontal  branch  thereto  throughout  its  length, 
wherever  this  branch  is  not  larger  than  2l/2  in.  diameter.  When 
larger,  reductions  in  the  riser  can  be  made  until  2l/2  in.  is 
reached  when  this  size  should  be  maintained  throughout  the 
remainder  of  its  length.  No  riser  should  be  made  less  than 
2^  in.  unless  a  lift  is  necessary. 

Before  finally  fixing  the  size  of  riser  to  be  used  in  any 
case  the  size  of  the  branch  in  the  horizontal  lines  serving  the 
same  must  be  approximately  determined. 

These  sizes  will  be  dependent  on  the  location  in  which  it  is 
necessary  to  install  the  vacuum  producer.  In  the  case  of  the 
building  (Fig.  61)  the  most  desirable  location  for  the  vacuum 
producer  will  be  in  the  exact  center  of  the  building. 

With  the  vacuum  producer  centrally  located  the  longest  run 
from  any  riser  will  be  55  ft.    To  this  we  must  add: 
5  ft.  for  each  long-turn  elbow. 

10  ft.  for  each  short-turn  elbow. 

10  ft.  for  entrance  to  each  long  sweep  Y  branch. 

20  ft.  for  entrance  to  a  tee  branch,  except  at  sweeper  inlets 
on  risers,  where  10  ft.  is  ample 

In  calculating  the  riser  friction  for  risers  under  150  ft.  in 
length  the  whole  capacity  of  the  riser  can  be  assumed  as  being 
connected  to  a  point  midway  of  its  length. 

In  the  eight-story  building  (Fig.  61)  the  length  of  the  riser 
from  basement  ceiling  to  eighth  floor  will  be  100  ft.  and  the 
length  to  be  figured,  50  ft.  The  equivalent  length  of  pipe  line 
for  any  of  the  risers,  with  the  vacuum  producer  centrally 
located,  will  be : 


PIPE  AND  FITTINGS  117 

From  entrance  tee   into  riser    10  ft. 

Length  of  riser,  one-half  total  length 50  ft. 

Turn  at  base  of  riser   10  ft. 

Run  in  basement    55  ft. 

Y  branch  or  elbow   10  ft. 

Elbow  at  separator  5  ft. 


Equivalent    length    140  ft. 

Each  riser  is  to  serve  two  sweepers  and  must  pass  140  cu.  ft. 
of  free  air  per  minute.  This  will  give  a  friction  loss  in  a 
2^ -in.  pipe  of  2  in.  mercury,  if  10  in.  mercury  be  maintained 
at  the  hose  cock  and  1-in.  hose  used ;  and  1.5  in.  mercury  if  6  in. 
mercury  be  maintained  at  the  hose  cock  and  1^4 -in.  hose  used. 
Either  of  these  figures  are  within  the  limits  set  for  the  maxi- 
mum friction  loss  and  2^2 -in.  pipe  will  be  the  proper  size 
for  the  risers  and  their  branches  in  the  basement. 

The  portion  of  the  main  in  the  basement  that  serves  the  two 
risers  on  either  side  of  the  building  (portion  "ab,"  Fig.  61) 
must  be  of  such  size  as  will  produce  the  same  loss  in  vacuum 
with  280  cu.  ft.  of  air  passing  as  the  2l/2 -in.  pipe  gives  with 
140  cu.  ft.  of  air  passing.  This  may  be  determined  from  any 
table  of  equalization  of  pipes  or  may  be  obtained  from  the 
chart,  Fig.  48,  in  the  following  manner: 

Find  the  intersection  of  the  horizontal  line  "140"  with  the 
diagonal  representing  a  2^4 -in.  pipe  and  pass  on  the  nearest 
vertical  to  its  intersection  with  the  horizontal  line  "280."  The 
diagonal  inclined  toward  the  left  passing  nearest  this  intersection 
will  be  the  pipe  size  required.  In  this  case  a  3-in.  pipe  will 
give  a  slightly  greater  friction  and  will  be  sufficient. 

Unfortunately,  it  is  rarely  possible  to  locate  the  vacuum  pro- 
ducer in  as  favorable  a  point  as  that  given  in  the  illustration, 
but  an  effort  should  always  be  made  to  select  a  location  as 
nearly  central  to  all  risers  as  possible.  The  basements  of  mod- 
ern office  buildings  are  generally  crowded  and  the  space  assigned 
to  the  mechanical  equipment  is  limited  and  owing  to  the  neces- 
sity of  ventilation,  the  vacuum  producer  is  generally  located 
near  the  outside  of  the  building. 


118 


VACUUM    CLEANING    SYSTEMS 


Probably  the  best  locatipn  that  could  be  obtained  in  this  case 
would  be  at  "d"  (Fig.  62).  The  length  of  piping  to  risers  1 
and  2  would  now  be  the  same  as  that  to  all  risers  in  case  of 
Fig.  61,  but  the  distance  to  risers  3  and  4  will  be  increased  50 
ft.  It  will  be  possible  to  increase  the  size  of  the  pipe  lino 
"bd"  to  the  maximum  size  to  serve  four  sweepers,  or  3^  in., 
the  risers  and  their  branches  to  remain  2j/2  in. 

The  total  friction  loss  to  risers  1  and  2  will  now  be: 

Entrance  to  tee  in  risers,  10  ft.  plus  50  ft 60  ft. 

Turn  at  base  of  riser,  10  ft.,  branch  from  "c" 

to  riser  32  ft 42  ft. 

Entrance  to  tee  in  main   .  20  ft. 


Total  equivalent  length  of  2^ -in.  pipe 122  ft. 

When  1-in.  hose  is  used  the  density  of  the  air  entering  the 
2^2 -in.  pipe  is  equivalent  to  a  vacuum  of  10  in.  mercury  and 
the  friction  loss  in  the  23/2 -in.  pipe  will  be  1.9  in.  mercury. 


2 1 


FIG.  62. 


ELEVATION  OF  LAYOUT  FOR  OFFICE  BUILDING,  SHOWING 
BEST  LOCATION  (AT  D)  FOR  VACUUM  PRODUCER. 


When  1^4 -in.  hose  is  used,  the  density  of  the  air  entering  the 
pipe  will  be  equivalent  to  a  vacuum  of  6-in.  mercury  and  the 
friction  loss  in  the  2^ -in.  pipe  will  be  1.32  in.  mercury. 

The  density  of  the  air  entering  the  3^4 -in.  pipe,  "b  d,"  will 
be  equivalent  to  a  vacuum  of  11.9  in.  mercury  when  1-in.  hose 
is  used,  and  to  7.32  in.  mercury  when  1^4 -in.  hose  is  used. 
The  friction  loss  in  the  3^ -in.  pipe  will  be  0.31  and  0.23  in. 


PIPE  AND  FITTINGS  119 

mercury,  respectively.  Total  friction  loss  to  inlets  on  risers 
1  and  2  will  be  2.21  in.  with  1-in.  hose  in  use,  and  1.55  in.  with 
1^4 -in.  hose. 

To  obtain  the  friction  loss  to  inlets  on  risers  3  and  4  the 
friction  loss  in  the  pipe  "be"  must  be  added  to  the  above 
figures.  With  50  ft.  of  3^-in.  pipe  carrying  280  cu.  ft.  free 
air  the  friction  loss  is  0.6  in.  when  the  vacuum  in  the  pipe  is 
12  in.  and  0.4  when  the  vacuum  in  the  pipe  is  8  in. 

The  total  loss  of  vacuum  to  inlets  on  risers  3  and  4  will  be  2.91 
in.  if  1-in.  hose  is  used  and  1.95  in.  if  1^4-in.  hose  is  used.  In 
this  case,  the  total  loss  from  inlet  to  vacuum  producer  is  ap- 
proximately equal  to  the  maximum  variation  of  vacuum  per- 
mitted at  sweeper  outlets  when  1%-m.  hose  is  used,  but  is 
greater  than  when  1-in.  hose  is  used. 

However,  it  is  the  variation  in  vacuum  at  the  hose  cock 
farthest  from  and  that  nearest  to  the  vacuum  producer  thajt 
fixes  the  maximum  variation  allowable.  In  this  case  it  will  be 
the  difference  in  vacuum  between  an  inlet  on  riser  1  or  2  and  a 
similar  inlet  on  riser  3  or  4.  The  difference  in  vacuum  at  the 
bases  of  these  risers  will  be  the  friction  loss  in  the  pipe  "be," 
and  the  total  difference  in  friction  in  the  risers  will  occur  when 
one  sweeper  is  attached  to  the  lowest  inlet  on  one  riser,  and 
one  sweeper  on  the  eighth  and  one  on  the  seventh  floor  on  the 
other  riser.  The  friction  loss  in  the  riser  having  the  two 
sweepers  attached  to  its  upper  inlets  will  be : 

15  ft.  of  2^ -in.  pipe  from  seventh  to  eighth  floors,  70  cu.  ft. 
of  free  air  per  minute,  or  0.051  in.  with  a  density  equivalent 
to  6-in.  vacuum,  and  0.075  in.  with  a  density  equivalent  to  10- 
in.  vacuum. 

85  ft.  of  2^2 -in.  pipe  from  first  to  seventh  floors,  140  cu.  ft. 
free  air  per  minute,  or  0.25  in.  with  a  density  equivalent  to 
6-in.  vacuum,  and  0.42  in.  with  a  density  equivalent  to  10-in. 
vacuum. 

The  total  difference  in  vacuum  at  the  hose  cocks  will  be : 

0.051-f-0.25-f0.4=0.7  in.  with  6-in.  vacuum  at  the  hose  cock. 

0.075-|-0.42-j-0.6=1.15  in.  with  10-in.  vacuum  at  the  hose  cock. 

Either  of  these  values  are  well  within  the  maximum  varia- 
tion. It  is,  therefore,  evident  that  when  the  vacuum  producer 


120  VACUUM    CLEANING    SYSTEMS 

cannot  be  centrally  located  that  a  piping  system  which  will 
give  the  most  nearly  equal  length  of  pipe  to  each  riser  will 
yield  the  best  results. 

A  vacuum  cleaning  system  for  serving  a  passenger  car  stor- 
age yard  will  best  illustrate  the  effect  of  long  lines  of  piping. 
A  typical  yard  having  8  tracks,  each  of  sufficient  length  to 
accommodate  10  cars,  is  shown  in  Fig.  63.  The  vacuum  pro- 
ducer in  this  case  is  located  at  the  side  of  the  yard  at  one  end, 
which  is  not  an  unusual  condition. 

The  capacity  of  this  yard  will  be  80  cars  which  must  gen- 
erally be  cleaned  between  the  hours  of  midnight  and  6  A.  M., 
or  a  period  of  6  hours  for  cleaning. 

It  will  require  one  operator  approximately  20  minutes  to 
thoroughly  clean  the  floor  of  one  car,  on  account  of  the  difficulty 
in  getting  under  and  around  the  seat  legs.  In  addition  to  this, 
it  is  also  necessary  to  clean  the  upholstery  of  the  seats  and  their 
backs,  which  will  require  approximately  25  minutes  more  or 
45  minutes  for  one  operator  to  thoroughly  clean  one  car. 
Therefore,  one  operator  can  clean  8  cars  during  the  cleaning 
period  and  a  ten-sweeper  plant  will  be  necessary  to  serve  the 
yard. 

One  lateral  cleaning  pipe  must  be  run  between  every  pair  of 
tracks  or  four  laterals  in  all  to  properly  reach  all  cars  without 
running  the  hose  across  tracks  where  it  might  be  cut  in  two 
by  the  shifting  of  trains. 

Outlets  should  be  spaced  two  car  lengths  apart  in  order  to 
bring  an  outlet  opposite  the  end  of  every  second  car.  This  will 
make  it  possible  to  bring  the  hose  in  through  the  end  of  the 
car  at  the  door  opening  and  clean  the  entire  car  from  one  end 
which  can  be  done  by  using  100  ft.  of  hose.  The  use  of  double 
the  number  of  outlets  and  50  ft.  of  hose  would  require  two  at- 
tachments of  the  hose  to  clean  one  car  resulting  in  a  loss  of 
time  in  cleaning  and  is  not  recommended. 

In  this  case,  100  ft.  of  hose  would  be  the  shortest  length  that 
would  be  likely  to  be  used  and  60  cu.  ft.  of  free  air  would  be  the 
maximum  to  be  allowed  for  when  using  1*4 -in.  hose. 

The  simplest  layout  for  a  piping  system  to  serve  this  yard 
would  be  that  shown  in  Fig.  63. 


PIPE  AND  FITTINGS 


121 


When  the  entire  yard  is  filled  with  cars  and  the  entire  force 
of  ten  operators  is  started  to  clean  them  it  would  be  possible  to 
so  divide  them  that  not  over  three  operators  would  be  working 
on  any  one  lateral  and  this  condition  will  be  assumed  to  exist. 
The  maximum  size  for  the  laterals  between  the  tracks  will  be 
that  for  three  sweepers,  or  3  in.,  and  it  will  not  be  safe  to  use 
this  size  beyond  the  second  inlet  from  the  manifold,  from  which 
point  to  the  end  of  the  lateral  it  must  be  made  2^  in.,  the 
maximum  size  for  either  one  or  two  sweepers.  The  total  loss 
of  pressure  due  to  friction  from  the  inlet  at  x  (Fig.  63)  to 
the  separator  can  be  readily  calculated  from  the  chart  (Fig. 
56)  as  follows: 

TABLE  20. 

PRESSURE  LOSSES  FROM  INLET  TO  SEPARATOR  IN  SYSTEM  FOR  CLEANING 
RAILROAD  CARS. 


Section 
of  Pipe. 

Cubic  Ft. 
Free  Air 
per  min. 

Equiv- 
alent 
Length, 
feet. 

Size  of 
Pipe, 
In.  Diam. 

Average 
Vacuum 
Ins. 
Mer- 
cury. 

Friction 
Loss, 
Ins. 
Mercury. 

Final 
Vacuum, 
Ins. 
Mercury. 

x—  5 
5—4 
4—2 
2—  w 
w  —  u 
u  —  s 
s  —  sep 

60 

120 
180 
180 
360 
480 
600 

150 
140 
280 
190 
20 
20 
20 

2^ 
2^ 
2^ 
3 
5 
6 
6 

6 
7 
11 
16 
19 
20 
20 

0.35 
1.35 
7.0 
4.0 
0.9 
0.5 
0.4 

6.35 
7.70 
14.70 
18.70 
19.60 
20.10 
20.50 

This  loss  will  be  the  maximum  that  is  possible  under  any 
condition  as  it  is  computed  with  three  sweepers  working  on  the 
three  most  remote  inlets  on  laterals  "xy"  and  "vw"  and  with 
two  sweepers  on  laterals  "tu"  and  "rs."  The  pipes  are  the 
largest  which  will  give  a  velocity  of  40  ft.  per  second  with  the 
full  load  and  at  the  density  which  will  actually  exist  in  the 
pipe  lines  with  the  vacuum  maintained  at  the  separator  of 
20  in.  mercury  in  all  cases,  except  the  pipe  from  "s"  to  sepa- 
rator. There  the.  size  was  maintained  at  6  in.,  as  it  was  not 
considered  advisable  to  increase  this  on  account  o*f  the  reduced 
velocity  which  would  occur  when  less  than  the  total  number  of 
sweepers  might  be  working. 

As  bare  floor  brushes  will  be  used  for  cleaning  coaches  it  is 
not  considered  advisable  to  reduce  the  air  quantity  below  that 


122  VACUUM    CLEANING    SYSTEMS 

required  by  such  renovators.  However,  when  carpet  renovators 
are  used  in  Pullman  cars  and  upholstery  renovators  are  used 
on  the  cushions  of  both  coaches  and  Pullmans,  the  air  quantity 
will  be  reduced.  This  condition  may  exist  at  any  time,  also 
one  of  these  carpet  or  upholstery  renovators  may  be  in  use  on 
one  of  the  inlets  most  remote  from  the  separator  at  the  same 
time  that  nine  floor  brushes  are  in  use  on  the  remaining  out- 
lets. In  that  case  a  vacuum  at  the  separator  of  less  than  20  in. 
would  result  in  a  decrease  in  the  vacuum  at  the  inlet  to  which 
this  renovator  was  attached.  The  vacuum  at  the  separator  must, 
therefore,  be  maintained  at  the  point  stated. 


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FIG.  63.   VACUUM  CLEANING  LAYOUT  FOR  A  PASSENGER  CAR 
STORAGE  YARD. 

With  such  a  vacuum  there  will  be  variation  in  the  vacuum 
at  the  hose  cocks  of  from  6  in.  to  20  in.  or  seven  times  the 
maximum  allowable  variation  in  vacuum  at  the  hose  cocks. 

If  1-in.  hose  be  used,  the  maximum  air  quantities  will  be  40 
cu.  ft.  per  sweeper  If  we  start  with  a  vacuum  at  the  inlet 
"x"  of  10-in.  mercury,  the  vacuum  at  the  separator  will  again 
be  20  in.  and  we  now  have  a  variation  of  10  in.  between  the 
nearest  and  most  remote  inlet  from  the  separator,  or  five  times 
the  maximum  allowed. 

Either  of  these  conditions  is  practically  prohibitive,  due  to : 


PIPE  AND  FITTINGS  123 

1.  The  excessive  power  consumption  at  the  separator.  50  H.  P. 
in  case  1^4 -in.  hose  is  used,  and  33  H.  P.  in  case  1-in.  hose 
is  used. 

2.  The  excessive  capacity  of  the  exhauster  in  order  to  handle 
the  air  at  such  low   density,   a  displacement  of  1,800  cu.   ft. 
being  necessary  in  case  1^-in.  hose  is  used  and  1,200  cu.  ft. 
in  case  1-in  hose  is  used. 

3.  The  great  variation  in  the  vacuum  at  the  hose  cocks  which 
will  admit  the  passage  of  so  much  more  air  through  a  brush 
renovator  on  an  outlet  close  to  the  separator  as  to  render  use- 
less the  calculations  already  made,  or  the  high  vacuum  at  the 
carpet  or  upholstery  renovators  would  render  their  operation 
practically  impossible. 


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FIG.  64.   ARRANGEMENT  OF  PIPING  RECOMMENDED  AS  BEST  FOR 
PASSENGER  CAR  STORAGE  YARD. 

Such  a  layout  must  be  at  once  dismissed  as  impractical,  and 
some  other  arrangement  must  be  adapted.  The  arrangement  of 
piping  shown  in  Fig  64  is  considered  by  the  author  to  be  the 
best  that  can  be  devised  for  this  case. 

With  this  arrangement  the  vacuum  at  the  separator  must  be 
maintained  at  11.50  in.  mercury  to  insure  a  vacuum  of  6  in. 
mercury  at  the  outlet  "x"  under  the  most  unfavorable  con- 
ditions, and  the  maximum  variation  in  vacuum  at  the  inlets  will 
be  3.45  in.  mercury  when  1^4 -in.  hose  is  used.  This  will  give 
a  maximum  vacuum  under  a  carpet  renovator  of  ll/2  in.  mer- 


124  VACUUM    CLEANING    SYSTEMS 

•cury  with  37  cu.  ft.  of  air  passing  and  will  permit  70  cu.  ft. 
of  free  air  per  minute  to  pass  a  brush  renovator  when  operating 
with  100  ft.  of  hose  attached  to  the  inlet  at  which  the  highest 
vacuum  is  maintained.  Both  of  these  conditions  will  permit 
satisfactory  operation  and  the  increased  air  quantities  will  not 
seriously  affect  the  calculations  already  made.  The  maximum 
horse  power  required  at  the  separator  will  now  be  20.5  as 
against  over  50  in  the  case  of  the  piping  arrangement  shown  in 
Fig.  63,  and  will  require  an  exhauster  having  a  displacement  of 
950  cu.  ft.  instead  of  1,800  cu.  ft.  required  with  the  former 
layout. 

If  1-in.  hose  is  used  and  10  in.  mercury  maintained  at  the 
outlet  "x"  under  the  same  conditions  as  before,  the  vacuum 
at  the  separator  will  be  14.50  in.  and  the  maximum  variation 
in  the  vacuum  at  the  inlets  will  be  3  in.,  which  will  give  a 
maximum  vacuum  under  a  carpet  renovator  of  6  in.  mercury 
with  32  cu.  ft.  of  air  passing  and  will  permit  the  passage  of 
45  cu.  ft.  of  free  air  through  a  brush  renovator  when  operated 
at  the  end  of  100  ft.  of  hose  attached  to  the  outlet  at  which 
the  highest  vacuum  is  maintained.  This  is  a  more  uniform  re- 
sult, than  was  noted  when  1)4 -in.  hose  was  used. 

The  maximum  horse  power  which  will  be  required  at  the 
separator  will  now  be  18.6  and  the  maximum  displacement  in 
the  exhauster  will  be  740  cu.  ft. 

It  is,  therefore,  evident  that,  where  very  long  runs  of  piping 
are  necessary  and  where  100  ft.  of  hose  will  always  be  necessary, 
the  use  of  1-in.  hose  will  require  less  power  and  a  smaller  dis- 
placement exhauster  than  would  be  required  with  1)4 -in.  hose, 
without  affecting  the  efficiency  of  the  cleaning  operations,  and 
at  the  same  time  rendering  the  operation  of  the  renovators  on 
extreme  ends  of  the  system  more  uniform. 

The  example  cited  in  Figs.  63  and  64  is  not  by  any  means  an 
extreme  case  to  be  met  in  cleaning  systems  for  car  yards,  and 
the  larger  the  system  the  greater  will  be  the  economy  obtained 
with  1-in.  hose. 

Such  conditions,  however,  are  confined  almost  entirely  to  lay- 
outs of  this  character  and  will  seldom  be  met  in  layouts  within 
any  single  building.  This  is  fortunate,  as  the  train  cleaning  is 


PIPE  AND  FITTINGS 


125 


practically  the  only  place  where  the  use  of  100  ft.  of  hose  can 
be  assured  at  all  times. 

Very  tall  buildings  offer  a  similar  condition  although  the 
laterals  are  now  vertical  and  can  be  kept  large  enough  to  suf- 
ficiently reduce  the  friction  without  danger  of  deposit  of  dirt 
in  them,  and  the  horizontal  branches  will  be  short  and  also 
large  enough  to  keep  the  friction  within  reasonable  limits  with- 
out danger  of  deposit  of  dust. 

Where  large  areas  within  one  or  a  group  of  buildings  must 
be  served  by  one  cleaning  system,  better  results  can  often  be 
obtained  by  installing  the  dust  separator  at  or  near  the  center 
of  the  system  of  risers  instead  of  close  to  the  vacuum  producer, 
as  indicated  in  Fig.  65.  When  this  is  done,  the  pipe  leading 


c 

< 

i 
Separator 

•)                          r 

•) 

J  Vacuum  Producer 

( 
< 

"\| 

J^ 

c 

1                               C 

Clean  Air  Line 

FIG.  65.   GOOD  LOCATION  FOR  DUST  SEPARATOR  WHERE  LARGE 
AREAS  ARE  SERVED  BY  ONE  CLEANING  SYSTEM. 

from  the  separator  to  the  vacuum  producer  carries  only  clean 
air  and  can  be  made  as  large  as  desired  and  the  friction  loss  re- 
duced, resulting  in  a  considerable  reduction  in  the  power  re- 
quired to  operate  the  system. 

Where  the  system  becomes  still  larger,  two  or  more  separators 
located  at  centers  of  groups  of  risers  can  be  used  and  clean 
.air  pipes  of  any  desired  size  run  to  the  vacuum  producer  (Fig. 
66).  When  more  than  one  separator  is  used  care  should  be 
exercised  in  proportioning  the  pipe  lines  from  the  separators 
to  the  vacuum  producer  so  as  to  have  the  friction  loss  from  the 
vacuum  producer  to  each  separator  the  same  in  order  to 
.give  uniform  results  at  all  inlets.  This  loss  should  also  be 


126 


VACUUM    CLEANING    SYSTEMS 


kept  as  low  as  possible  in  order  to  prevent  a  higfti  vacuum 
in  a  separator  serving  a  portion  of  the  system  on  which  few 
sweepers  are  in  operation.  If  low  friction  losses  in  the  clean  air 
pipe  will  require  larger  pipes  than  it  is  practical  or  economical 
to  install,  pressure  reducing  valves  might  be  located  in  the 
clean  air  pipes  near  the  separators  to  so  regulate  the  vacuum 
at  the  separators  and  insure  uniform  results.  A  system  of  this 
kind  might  serve  several  premises  and  the  air  used  by  each  be 
metered  and  the  service  sold  much  the  same  as  heat  and  elec- 
tricity. However,  the  power  required  to  operate  the  system 
would  be  greater  than  that  needed  to  operate  a  similar  num- 


IO 


Clean  Air  Line 


CD 


FIG.    66. 


LOCATION    OF    SEPARATORS    AT    CENTERS    OF    GROUPS    OF 
RISERS    FOR    LARGE    SYSTEMS. 


ber  of  sweepers  by  individual  plants  owing  to  the  higher  vac- 
uum required  to  overcome  the  friction  in  the  trunk  mains. 
This  would  be  offset  by  the  use  of  larger  units  and  the  possi- 
bility of  operating  them  at  full  load  at  nearly  all  times.  A 
system  of  this  kind  was  contemplated  in  Milwaukee  some  seven 
years  ago,  but  was  never  installed. 

The  question  of  pipe  friction  in  connection  with  the  design 
of  vacuum  cleaning  systems  requires  careful  consideration, 
much  more  than  it  ever  received  in  the  early  days  of  the  art 
and  a  great  deal  more  than  it  sometimes  receives  at  the  present 
time. 


CHAPTER  VIII. 

SEPARATORS. 

The  appliances  which  remove  the  dust  from  the  air  current 
which  has  carried  it  through  the  hose  and  pipe  lines,  in  order 
to  prevent  damage  to  the  vacuum  producer,  play  an  important 
part  in  the  make-up  of  a  vacuum  cleaning  system. 

Classification  of  Separators. — Separators  may  be  divided  in- 
to two  classes  according  to  their  use: 

1.  Partial  separators,  which  must  be  used  in  conjunction  with 
another  separator  in  order  to  effect  a  complete  removal  of  the 
dust  from  the  air.     These  separators   are  again  divided  into 
two  sub-classes,  i.   e.,  primary,  or  those   removing  the  heavy 
particles  of  dust  and   dirt  only,   and  secondary,  or  those  re- 
moving the  finer  particles  of  dirt  which  have  passed  through  the 
primary  separator. 

2.  Complete  separators,  or  those  in  which  the  removal  of  both 
the  heavy  and  the  finer  particles  of  dust  is  effected  in  a  single 
separator. 

Separators  may  also  be  classified,  according  to  the  method 
employed  in  effecting  the  separation,  into  dry  separators  in 
which  all  operations  are  effected  without  the  use  of  liquid,  and 
wet  separators  in  which  water  is  employed  in  the  removal  of 
the  dust. 

Primary  Separators. — Primary  separators  are  nearly  always 
operated  as  dry  separators  and  depend  largely  on  centrifugal 
force  to  effect  the  separation.  The  first  type  of  primary  sepa- 
rator used  by  the  Vacuum  Cleaner  Company  is  illustrated  in 
Fig.  67.  This  consists  of  a  cylindrical  tank,  with  hopper  bottom, 
containing  an  inner  cylinder  fixed  to  the  top  head.  The  dust- 
laden  air  enters  the  outer  cylinder  near  the  top  on  a  tangent 
to  the  cylinder.  The  centrifugal  action  set  up  by  the  air  strik- 
ing the  curved  surface  of  the  outer  cylinder  tends  to  keep  the 

127 


128 


VACUUM    CLEANING    SYSTEMS 


heavy  dirt  near  the  outside  of  same,  and  as  it  falls  towards  the 
bottom  the  velocity  is  reduced  and  its  ability  to  carry  the  dust 
is  lost.  When  the  air  passes  below  the  inner  cylinder  the  veloc- 
ity is  almost  entirely  destroyed  and  all  but  the  very  lightest  of 
the  dust  particles  fall  to  the  bottom,  while  the  air  and  the  light 
dust  particles  find  their  way  out  of  the  separator  through  the 
opening  in  the  center  at  the  top. 


rf? 


PIG.  67.  EARLY  TYPE  OF  PRI- 
MARY SEPARATOR,  USED  BY 
VACUUM  CLEANER  COMPANY. 


FIG.  68.  PRIMARY  SEPARATOR 
USED  BY  THE  SANITARY  DE- 
VICES MANUFACTURING  COM- 
PANY. 


The  primary  separator  used  by  the  Sanitary  Devices  Manu- 
facturing Company  is  illustrated  in  Fig  68.  The  inner  cen- 
trifugal cylinder  is  omitted  and  the  air  enters  through  an  elbow 
in  the  top  of  the  separator,  near  its  outer  extremity,  which  is 
turned  at  such  an  angle  that  the  air  is  given  a  whirling  motion 


SEPARATORS 


129 


resulting  in  the  dust  being  separated  much  the  same  as  in  the 
case  of  the  Vacuum  Cleaner  Company's  apparatus. 

Either  of  these  separators  will  remove  from  95%  to  98% 
of  the  dirt  that  ordinarily  comes  to  them  through  the  pipe  lines 
and  are  about  equally  efficient. 

The  separator  illustrated  in  Fig.  69  was  used  by  the  General 
Compressed  Air  and  Vacuum  Cleaning  Company.  The  enter- 
ing air  is  led  to  the  center  near  the  bottom  and  is  then  released 
through  two  branches  curved  to  give  the  air  a  whirling  motion. 
The  clean  air  is  removed  from  the  center  of  the  separator  near 

ft 


FIG.  69.  PRIMARY  SEPARATOR 
USED  BY  THE  GENERAL  COM- 
PRESSED AIR  AND  VACUUM 
CLEANING  COMPANY. 


FIG.  70.  PRIMARY  SEPARATOR 
MADE  BY  THE  BLAISDELL 
ENGINEERING  COMPANY. 


the  top.  This  separator  is  not  as  effective  in  its  removal  of  dirt 
as  either  of  the  former  types,  owing  <to  the  entering  air 
being  introduced  near  the  bottom  This  tends  to  keep  the  air 
and  the  dust  in  the  bottom  of  the  separator  continually  stirred 
up,  also  the  curved  inlets  give  the  air  more  of  a  radial  than  a 
tangential  motion  and  there  is  less  separation  due  to  centrifugal 
action. 


130  VACUUM    CLEANING    SYSTEMS 

The  separator  illustrated  in  Fig.  70  is  made  by  the  Blaisdell 
Engineering  Company.  In  this  separator  the  inner  centrifugal 
cylinder  of  the  Vacuum  Cleaner  Company's  separator  is  re- 
placed by  a  spiral  extending  nearly  to  the  outlet  in  the  center 
of  the  top.  This  arrangement  tends  to  prevent  the  reduction  in 
the  air  velocity  and  to  limit  its  effectiveness  in  the  removal 
of  dust. 

Separators  similar  to  the  Sanitary  separator  have  been  manu- 
factured by  many  firms  producing  vacuum  cleaning  systems. 
These  all  differ  somewhat  in  details  of  construction  but  the 
principle  involved,  i.  e.,  centrifugal  force  and  reduction  in  air 
velocity,  is  the  same  in  all  cases. 

With  vacuum  producers  in  which  there  are  no  close  clear- 
ances or  rubbing  contacts,  these  are  the  only  separators  used. 
The  finer  particles  of  dust  passing  these  separators  are  carried 
harmlessly  through  the  vacuum  producer  and  through  the  ex- 
haust to  the  outer  atmosphere  or  to  the  chimney  or  other  flue 
where  they  are  effectively  sterilized. 

Secondary  Separators. —  With  vacuum  producers  having 
close  clearances  or  rubbing  parts  in  contact  with  each  other  and 
the  air  exhausted,  further  separation  of  the  finer  dust  particles 
is  necessary.  To  accomplish  this,  secondary  separators  are  used. 
All  of  the  early  systems  used  a  wet  separator  as  a  secondary 
separator.  That  used  by  the  Vacuum  Cleaner  Company  is  illus- 
trated in  Fig.  71.  It  consists  of  a  cylindrical  tank  partially 
filled  with  water,  with  a  diaphram  perforated  in  the  central 
portion  and  fixed  in  place  below  the  water  line,  and  an  inverted 
frustrum  of  a  cone  placed  just  above  the  water  line.  The  air 
enters  the  separator  below  the  water  line  and  passes  up  through 
the  water  in  the  form  of  small  bubbles  which  are  broken  up  into 
still  smaller  bubbles  on  passing  through  the  perforations  in 
the  diaphram.  This  action  is  very  essential  to  the  thorough 
cleansing  of  the  air,  as  large  bubbles  of  air  may  contain  en- 
trapped dust  which  will  pass  through  the  water  and  out  into 
the  vacuum  producer.  The  inverted  frustrum  of  a  cone  is  in- 
tended to  prevent  any  entrained  water  passing  out  of  the  sepa- 
rator with  the  air.  This  separator  has  always  given  satisfactory 
results  when  used  in  connection  with  reciprocating  pumps. 


SEPARATORS 


131 


The  separator  illustrated  in  Fig.  72  was  manufactured  by  the 
General  Compressed  Air  and  Vacuum  Cleaning  Company.  The 
air  enters  the  separator  through  the  pipe  curved  downward  and 
escapes  at  the  center  below  the  water  line.  It  then  rises  in  the 
form  of  bubbles  and  most  of  it  strikes  the  under  side  of  the 
ribbed  aluminum  disc  "a,"  which  is  intended  to  float  on  the 
surface  of  the  water,  and  passes  along  the  ribbed  under  surface 
of  this,  disc,  escaping  into  the  upper  part  of  the  separator  around 
the  edge. 

The  clean  air  passes  out  of  the  top  of  the  separator  to  the 
vacuum  producer.  The  successful  operation  of  this  separator  is 


Water  L'me- 


FIG 


71.  SECONDARY  SEPARA- 
TOR USED  BY  THE  VACUUM 
CLEANER  COMPANY. 


FIG.  72.  SECONDARY  SEPARA- 
TOR USED  BY  THE  GENERAL 
COMP*RESSED  AIR  AND 
VACUUM  CLEANING  COMPANY. 


dependent  on  the  freedom  of  motion  of  the  disc  "a,"  which  will 
always  keep  it  on  the  surface  of  the  water,  and  on  all  of  the 
air  passing  up  through  the  water  under  the  disc. 

Should  the  disc  become  caught  on  the  supporting  pipe  the 
violent  agitation  of  the  water,  which  occurs  when  the  system 
is  in  operation,  will  cause  the  disc  to  be  left  high  and  dry  above 
the  water  at  times,  and  submerged  at  other  times.  When  this 
disc  is  above  the  water  line  it  will  not  break  up  any  of  the 
large  bubbles.  Also,  when  there  is  a  large  quantity  of  air  pass- 
ing through  the  separator,  there  is  great  likelihood  that  con- 
siderable of  the  air  bubbles  will  pass  up  through  the  water  en- 


132 


VACUUM    CLEANING    SYSTEMS 


tirely  outside  of  the  disc  and  these  bubbles  will  not  be  broken 
up.  This  separator  has  given  somewhat  unsatisfactory  results  in 
some  installations  tested  by  the  author. 

The  separator  used  by  the  Sanitary  Devices  Manufacturing 
Company  differs  from  those  already  described  in  that  the  air 
and  water  are  mixed  before  they  enter  the  separator  and  the 
air  comes  into  the  separator  above  the  water  line.  The  air  enters 
the  pipe  "a"  (Fig.  73)  and  passes  to  the  aspirator  "b,"  which 
is  connected  to  the  separator  by  the  pipe  "d"  below  the  water 
line  and  the  pipe  "e"  above  the  water  line.  The  excess  of 
vacuum  in  the  separator  draws  t!he  water  out  of  the  aspirator 


FIG.  73. 


SECONDARY  SEPARATOR  USED   BY  THE  SANITARY  DEVICES 
MANUFACTURING   COMPANY. 


and  its  pipe  connections  until  the  water  line  in  this  pipe 
is  lowered  below  the  top  of  the  horizontal  portion  of  the 
piping,  when  the  air  bubbles  up  through  the  demonstrator 
glass  "c"  and  passes  into  the  separator  through  the  pipe  "e." 
The  filling  of  the  vertical  pipe  leading  to  "c"  with  air  causes 
the  static  head  of  the  water  in  the  separator  to  produce  a  flow 
of  water  through  the  pipe  "d"  into  the  aspirator  "b."  This 
is  formed  in  the  shape  of  a  nozzle  and  the  water  enters  in  the 
form  of  a  spray  and  thoroughly  mixes  with  the  air.  The  cleans- 
ing action  of  this  water  spray  has  been  found  to  be  very 
effective  in  removal  of  all  fine  dust  and  this  separator  has  been 
found  to  be  the  most  effective  wet  separator  ever  produced. 


SEPARATORS  133 

While  the  wet  separator  when  properly  designed  will  effective- 
ly remove  the  finest  of  dust,  greasy  soot  will  not  emulsify  with 
the  water  and  its  removal  is  practically  impossible.  Fortu- 
nately, this  form  of  material  in  the  finely-divided  condition  in 
which  it  passes  the  primary  separator  is  not  gritty  and  does  not 
produce  injurious  effect  on  the  vacuum  producer. 

The  wet  separator  is  also  at  a  disadvantage  in  that  there  is  a 
loss  of  vacuum  in  passing  through  same  equal  to  the  head  of 
water  that  is  carried  between  the  inlet  and  the  surface  of  the 
water.  This  generally  amounts  to  nearly  2  in.  mercury. 

Means  must  be  provided  to  observe  the  height  of  the  water 
in  the  wet  separator.  For  this  purpose  a  glass  window  in  the 
side  of  the  separator  has  been  found  to  be  the  most  effective. 
The  use  of  an  ordinary  gauge  glass  such  as  is  used  on  boilers 
has  been  tried,  but  it  has  been  found  that  they  readily  become 
so  clouded  by  the  action  of  the  muddy  water  as  to  render  them 
useless  while  the  constant  agitation  of  the  water  against  the 
window  when  the  system  is  in  operation  tends  to  keep  the 
glass  clean. 

Dry  separators  have  been  used  for  secondary  separators  to 
a  limited  extent.  All  of  these  contained  a  bag  made  ©f  canvas 
or  some  other  fabric.  The  separator  illustrated  in  Fig.  74  con- 
tains a  bag  made  of  drilling  which  is  slightly  smaller  than  the 
inner  diameter  of  the  cylindrical  casing  of  the  separator.  The 
air  enters  the  inside  of  the  bag,  inflating  it,  and  passes  through 
the  bag  and  out  through  the  opening  in  one  side  of  the  casing. 
A  wire  guard  is  placed  over  this  opening  to  prevent  the  bag 
being  drawn  against  the  opening  and  thus  rendering  only  a 
small  portion  of  it  effective. 

These  bags  offer  very  little  resistance  to  the  passage  of  the 
air  when  they  are  clean  but  they  soon  become  filled  with  dust 
and  produce  an  increased  resistance  which,  if  neglected,  may 
result  in  so  great  a  difference  in  pressure  as  to  hinder  the  action 
of  the  system  and  result  in  the  rupture  of  the  bag,  letting  the 
dust  into  the  vacuum  producer. 

Some  trouble  has  been  experienced  in  finding  a  suitable  ma- 
terial through  which  the  dust  will  not  pass.  Hush  cloth,  such  as, 
used  on  dining  tables,  has  been  found  to  be  the  best  material 


134 


VACUUM    CLEANING    SYSTEMS 


for  this  purpose.  Better  results  are  obtained  by  passing  the 
air  from  the  outside  of  the  bag  towards  the  inside  than  when 
the  air  is  passed  as  indicated  in  Fig.  74.  When  this  arrange- 
ment is  adopted,  it  is  necessary  to  stretch  the  bag  over  a  metal 
screen  or  frame  in  order  to  prevent  collapse. 

Complete  Separators. —  Complete  separators  are  of  two  classes, 
i.  e.,  dry  and  wet.  The  first  complete  separator  that  the  author 
has  knowledge  of  was  used  by  the  Vacuum  Cleaner  Company, 
in  the  form  of  a  cylindrical  tank  and  contained  centrifugal 
cylinder  and  also  a  perforated  plate.  It  was  practically  a  com- 
bination of  the  separators  indicated  in  Figs.  67  and  71.  This 
separator  was  installed  in  connection  with  a  small  rotary  pump 


////  infiiir/tifr  // 

FIG.  74.   TYPE  OF  DRY  SEPARATOR  USED  AS  SECONDARY  SEPARATOR. 

and  mounted  on  a  truck.  It  worked  very  well  until  it  became 
filled  with  dirt  when,  in  one  case,  the  entire  contents  were 
ejected  into  an  apartment  in  which  it  was  being  used.  This 
separator  was  then  rebuilt  in  the  form  shown  in  Fig.  75,  the 
bag  being  made  of  hush  cloth  stretched  over  a  wire  screen.  The 
air  enters  the  cylinder  tangentially  and  much  of  the  separa- 


SEPARATORS 


135 


tion  is  accomplished  by  centrifugal  force,  the  remainder  of  the 
dust  being  removed  as  the  air  passes  through  the  bag.  This 
separator  was  successfully  used  as  long  as  this  company  con- 
tinued to  manufacture  such  apparatus. 

Another  form  of  complete  separator  quite  similar  to  that 
above  described  has  recently  been  brought  out  by  the  Electric 
Renovator  Manufacturing  Company  and  is  shown  in  section  in 
Fig.  76.  The  air  enters  this  separator  tangentially  below  the 
line  of  the  dust  bag,  Which  is  made  of  muslin  folded  back  and 
forward  over  a  set  of  concentric  cylinders  thus  giving  a  large 
area  for  the  passage  of  the  air.  Being  entirely  above  the  line 
of  the  entering  air,  none  of  the  heavy  dirt  strikes  the  bag 
and  what  dirt  is  caught  on  the  bag  is  on  the  lower  side  of  same 
and  is  shaken  off  every  time  the  bag  is  agitated.  This  agitation 


FIG.  75.   FORM  OF  COMPLETE  SEPARATOR  USED  BY  THE  VACUUM 
CLEANER  COMPANY. 

occurs  every  time  there  is  any  change  in  the  volume  of  air 
passing  the  separator,  and  when  these  separators  are  used  in 
connection  with  fan  type  of  exhausters  there  is  a  constant  surg- 
ing whenever  the  exhauster  is  operated  with  a  small  volume  of 
air  passing.  This  tends  to  keep  the  bag  clean  automatically. 

The  separator  illustrated  in  Fig.  77  is  manufactured  by  the 
American  Radiator  Company.  The  air  enters  this  apparatus 
through  the  pipe  in  the  center  and  passes  directly  down  to  the 
bottom,  the  velocity  being  gradually  reduced  due  to  the  ex- 


136 


VACUUM    CLEANING    SYSTEMS 


pansion  of  the  air  as  it  passes  down  the  cone-shaped  inlet,  the 
heavy  dirt  falling  to  the  bottom.    The  air  then  passes  up  along 


PIG. 


COMPLETE    SEPARATOR    BROUGHT    OUT   BY    THE    ELECTRIC 
RENOVATOR    MANUFACTURING    COMPANY. 


the  inner  surface  of  the  cylindrical  shell  and  thence  through  the 
bag,  which  is  stretched  over  a  screen,  to  the  outlet.     In  this 


SEPARATORS 


137 


separator  we  see  the  first  case  in  which  centrifugal  action  is  not 
utilized  in  separating  the  heavy  dust,  the  makers  evidently  con- 


no.    77. 


COMPLETE  SEPARATOR   MADE   BY  THE   AMERICAN  RADIATOR 
COMPANY. 


sidering  the  reduction  of  air  velocity  and  the  action  of  gravi- 
tation to  be  ample.  This  bag  is  arranged  to  permit  the  air 
passage  from  the  outside  towards  the  inside  and  it  is  tapered 


138  VACUUM    CLEANING    SYSTEMS 

to  allow  the  dirt  to  fall  off.  The  vacuum  gauge  is  connected 
to  the  inner  and  outer  sides  of  the  bag  by  means  of  a  three-way 
cock  to  permit  of  measuring  the  difference  in  vacuum  between 
the  inside  and  outside  of  the  bag  to  determine  when  the  bag  is 
in  need  of  cleaning,  which  is  accomplished  by  a  reversal  of  the 
air  current  through  the  bag.  This  is  quite  necessary  in  order  to 
keep  the  separator  always  in  an  efficient  condition. 

A  separator  was  devised  by  the  Sanitary  Devices  Manufac- 
turing Company  in  which  the  bag  was  held  extended  by  a  wire 
ring  having  a  weighted  rod  passing  out  through  the  top  of  the 
separator  attached  thereto.  When  the  bag  became  clogged  the 
difference  in  pressure  on  the  two  sides  would  result  in  a  tend- 
ency of  the  bag  to  collapse  and  the  rod  would  be  raised  up 
out  of  the  separator,  indicating  that  cleaning  was  necessary, 
which  could  be  easily  accomplished  by  drawing  the  rod  up  and 
down  a  few  times  thus  shaking  the  dust  off  the  bag.  This 
separator  never  came  into  general  use,  although  its  arrangement 
was  ingenious  and  should  have  been  easy  to  operate. 

The  great  difficulty  with  all  bags  which  must  be  cleaned 
periodically  is  that  they  are  almost  universally  neglected  even 
when  there  is  a  visual  indicator  to  show  the  accumulation  of 
dirt,  and  when  it  becomes  necessary  to  manipulate  a  three-way 
cock  in  order  to  ascertain  when  this  cleaning  must  be  done  it 
will  seldom  if  ever  be  attended  to.  A  bag  that  will  clean  itself, 
such  as  the  Capitol  Invincible,  is  shown  in  Fig.  76. 

The  separator  used  by  one  manufacturer  consists  of  a  simple 
cylindrical  tank  into  which  the  air  is  blown  tangentially,  with 
a  screen  near  the  top,  the  whole  forming  a  base  for  the  vacuum 
producer.  This  separator  does  not  remove  any  but  the  heaviest 
dirt  and  is  suitable  for  use  only  with  a  vacuum  producer  having 
very  large  clearances  and  in  locations  where  the  discharge  of 
considerable  dirt  into  the  atmosphere  is  not  objectionable. 

Total  Wet  Separator. — The  only  total  wet  separator  which 
is  in  commercial  use  is  manufactured  by  the  American  Rotary 
Valve  Company.  This  separator  is  contained  in  the  base  of  the 
vacuum  producer  and  is  provided  with  a  screen  near  the  point 
of  entrance  of  the  dust-laden  air,  which  screen  is  cleaned  by  a 
mechanically-driven  bristle  brush.  When  the  water  in  the 


SEPARATORS  139 

separator  becomes  foul,  the  contents  of  the  separator  are  dis- 
charged direct  to  the  sewer  by  means  of  compressed  air.  If 
this  separator  receives  proper  attention  it  makes  the  most  sani- 
tary arrangement  that  has  been  introduced  in  the  vacuum 
cleaning  line  to  date.  However,  the  separator  slhould  be  emptied 
at  frequent  intervals  or  the  volume  of  solid  matter  contained  in 
the  same  will  become  so  great  that  there  will  not  be  enough 
water  present  to  flush  the  sewer  and  stoppage  is  likely.  These 
separators  are  often  neglected  until  the  contents  become  of  the 
consistency  of  mortar  or  molasses  which  is  not  a  fit  substance 
to  discharge  into  a  sewerage  system. 

There  is  still  another  form  of  apparatus  used  in  connection 
with  vacuum  cleaning  systems  which  should  be  called  an  emul- 
sifier  rather  than  a  separator.  That  is  the  type  used  with  the 
Rotrex  and  the  Palm  systems.  The  dust  is  mixed  with  water 
when  it  first  enters  the  pump  chamber,  a  screen  being  used  to 
remove  the  lint  and  larger  particles  of  dirt  and  then  the  mud 
produced  by  thq  combination  of  the  dust  and  water  is  passed 
through  the  pump  along  with,  the  air.  The  air  and  muddy 
water  are  separated  on  the  discharge  side  of  the  vacuum  pro- 
ducer. In  many  cases  where  the  exhaust  pipe  is  long,  there  is 
considerable  back  pressure  on  the  discharge  which  is  often  suf- 
ficient to  force  the  seals  in  traps  on  the  sewerage  system,  allow- 
ing sewer  gas  to  be  discharged  into  the  building  in  which  the 
cleaning  system  is  installed.  No  means  are  provided  for  auto- 
matically cleaning  the  screen  used  in  these  appliances  and  the 
author  knows  of  cases  where  the  screen  has  become  so  com- 
pletely clogged  with  lint  that  its  removal  from  the  machine  was 
necessary  in  order  to  render  the  operation  of  the  cleaning  tools 
possible. 

When  dry  separators  are  used,  the  manual  removal  of  the  dry 
dirt  accumulated  is  necessary  and  is  an  objectionable  as  well  as 
unsanitary  operation.  The  author  considers  that  the  ideal 
arrangement  of  separator  would  be  one  in  which  the  dirt  can 
all  be  emulsified  with  water  and  retained  in  the  separator,  only 
the  air  passing  through  the  vacuum  producer,  and  in  which  the 
contents  of  the  separator  would  be  discharged  automatically  to 
the  sewer  when  the  density  of  this  mixture  becomes  as  heavy  as 


140 


VACUUM    CLEANING    SYSTEMS 


will  readily  run  through  the  sewer.  This  -discharge  should  be 
of  sufficient  volume  to  completely  fill  an  ordinary  house  sewer 
in  order  to  insure  a  thorough  flushing  of  the  drain,  and  should 
be  discharged  into  the  sewer  under  atmospheric  pressure  in 
order  to  guard  against  the  forcing  of  water  seals  in  any  of  the 
plumbing  fixtures. 


FIG.    77a. 


INTERIOR    CONSTRUCTION    OF    DUNN    VACUUM    CLEANING 
MACHINE. 


A  separator  of  this  type  has  recently  been  patented  by  E.  D. 
Dunn,  originator  of  the  Dunn  Locke  system.  It  is  illustrated  in 
Fig.  77a.  The  action  of  the  separator  is  as  follows:  After 
starting  the  motor  and  turning  on  a  small  quantity  of  water, 
a  vacuum  is  produced  in  one  tank  and  through  a  system  of 
piping  to  the  cleaning  implement  in  use.  The  dust  and  dirt 
collected  by  the  implement  is  saturated  as  it  approaches  the 


SEPARATORS  141 

plant  and  in  this  saturated  condition  enters  the  bottom  of  a 
body  of  water  in  the  tank. 

When  the  accumulating  dirt  and  water  reach  a  certain  level  a 
valve  is  automatically  operated  which  closes  the  tank's  commu- 
nication with  the  vacuum  pump  and  allows  its  contents  to  flow 
off  to  the  sewer  by  gravity.  The  mechanism  for  operating  the 
valve  is  rather  unique  and  includes  a  float  which,  on  rising 
with  the  water,  makes  a  positive  electrical  contact,  as  shown 
in  the  figure.  In  this  illustration  one  tank  is  about  to  dis- 
charge and  the  other  tank  is  about  to  become  operative.  The 
electrical  contact  causes  the  core  of  the  magnet  at  0'  to  rise, 
making  the  lever,  K,  turn  over,  which  action  opens  one  valve 
and  closes  the  other.  In  this  way  the  tanks  alternately  partly 
fill  and  empty  their  collections  of  water  'and  sweepings. 

This  system  has  not  as  yet  been  in  commercial  use  for 
a  sufficient  length  of  time  to  insure  its  successful  operation,  and 
the  author  does  not  consider  the  passing  of  dirt  and  water 
through  ordinary  check  valves  to  be  commercially  possible  with- 
out rendering  these  checks  inoperative. 

Check  valves  have  been  used  where  partial  wet  and  dry 
separators  are  operated  in  tandem  to  prevent  drawing  water 
into  the  dry  separator,  in  the  event  of  the  plant  being  shut 
down  with  all  inlets  on  the  pipe  line  closed.  In  such  a  case, 
the  leakage  through  the  pump  into  the  wet  separator  may  raise 
the  pressure  in  this  separator  faster  than  leakage  on  the  pipe 
line  raises  the  pressure  in  the  dry  separator. 

This  is  accomplished  by  providing  a  small  connection  between 
the  upper  part  of  the  two  separators,  fitted  with  a  check  valve 
opening  towards  the  dry  separator.  When  the  vacuum  pro- 
ducer is  in  operation,  the  vacuum  in  the  wet  separator  is 
approximately  2  in.  greater  than  that  in  the  dry  and  the  check 
is  held  closed.  When  the  vacuum  producer  is  stopped  and  the 
vacuum  in  the  wet  separator  falls  faster  than  in  the  dry  sepa- 
rator, this  check  opens  and  clean  air  passes  from  the  wet  to 
the  dry  separator.  When  operating  under  these  conditions,  the 
action  of  the  check  valve  is  satisfactory.  However,  the  author 
has  known  of  cases  where  the  check  leaked  and  when  this  hap- 
pened the  check  was  immediately  clogged  by  the  dust-laden 
air  from  the  dry  separator. 


CHAPTER  IX. 
VACUUM  PRODUCERS. 

The  next  portion  of  the  cleaning  system  is  that  which  pro- 
duces the  motion  of  the  air  through  the  system  and  that  to 
which  the  motive  power  is  applied,  namely,  the  vacuum  pro- 
ducer. 

Types  of  Vacuum  Producers. — Vacuum  producers  can  be 
divided  into  general  classes:  1.  Displacement  type,  in  which  a 
constant  volume  of  air  is  displaced  during  each  complete  cycle 
of  operations  of  the  machine,  'and  2.  Centrifugal  type,  in  which 
the  volume  of  air  passing  the  producer  during  each  complete 
cycle  of  operations  varies  with  the  resistance  to  the  passage  of 
such  air  through  the  system. 

Displacement  Type. —  Under  this  head  the  piston  and  rotary 
pumps  are  classed,  and  they  are  subdivided  according  to  con- 
struction into  reciprocating  and  rotary,  valved  and  valveless, 
air  cooled  and  water  cooled. 

Centrifugal  Type. — Under  this  head  the  fan  type  of  vacuum 
producers  are  classed.  They  may  be  divided,  according  to 
construction,  into  single  stage  and  multi-stage,  horizontal  and 
vertical. 

Power  Required  to  Produce  Vacuum. — In  order  to  ascer- 
tain the  efficiency  of  the  various  types  of  exhausters  to  be  dis- 
cussed in  this  chapter  it  is  necessary  to  ascertain  the  actual 
power  necessary  to  move  one  cubic  foot  of  free  air  at  any  degree 
of  vacuum. 

As  nearly  all  machines  tested  by  the  author  were  driven  by 
electric  motors  and  the  power  was,  therefore,  indicated  in  watts, 
the  curve  C-D  in  Fig.  78  showing  the  actual  power  necessary  to 
exhaust  one  cubic  foot  of  free  air  at  the  vacuum  noted  in  the 
lower  margin,  assuming  no  clearance  and  adiabatic  compres- 
sion, is  used  as  a  basis  for  calculation  of  efficiency.  This  shows 

142 


VACUUM  PRODUCERS 


143 


that  to  produce  a  vacuum  of  8  in.  mercury  there  will  be  re- 
quired an  expenditure  of  16  watts  for  each  cubic  foot  of  free 
air  exhaust eed,  and  to  produce  a  vacuum  of  12  in.  mercury  will 
require  an  expenditure  of  27  watts.  If  these  quantities  be 
divided  by  the  efficiency  of  the  machine  the  actual  power  re- 
quired will  be  determined. 


40 
30 

20 
10 

100 


™ 


Total  Power  Required  -fo Drive  Air  Compressor 

8        12        16        eo       Z4       u        3^ 


40 


&  10  \l 

Vacuum  Ins.  Mercury 

FIG.     78.      POWER    CONSUMPTION    AND    EFFICIENCY    OF    AIR    COM- 
PRESSOR  USED   AS   A   VACUUM   PUMP. 

Reciprocating  Pumps. — The  reciprocating  pump  was  used 
on  the  majority  of  the  earlier  vacuum  cleaning  systems.  The 
most  common  form  in  early  use  was  a  commercial  air  compressor 
which  was  used  as  a  vacuum  pump  without  any  change  in  its 
construction.  It  was  usually  fitted  with  mechanically-operated 
induction  and  poppet  type  of  eduction  valves  of  heavy  pattern, 
fitted  with  cushions  of  the  dash  pot  principle,  the  same  as  are 
used  on  air  compressors  working  against  terminal  pressures 
as  high  as  100  Ibs.  per  square  inch.  The  cylinders  were  water 
jacketed  to  remove  the  heat  of  high  compression.  The  valves  in 


144 


VACUUM    CLEANING    SYSTEMS 


these  compressors  were  heavy  and  required  considerable  pres- 
sure to  open  them  and  the  friction  of  the  valve  gear  and  other 
moving  parts,  which  were  made  heavy  enough  to  withstand  the 
strains  of  high  compression,  was  excessively  high  for  a  machine 
where  the  compression  did  not  exceed  8  or  9  Ibs.  per  square 
inch.  Their  efficiency,  therefore,  is  lower  under  actual  operat- 
ing conditions  than  if  they  were  working  against  pressures  for 
Which  they  were  designed.  A  curve  of  the  power  consumption 
of  a  14-in.  x  8-in.  Clayton  compressor  is  shown  on  Fig.  78, 
the  abscissae  being  the  vacuum  in  inches  of  mercury  and  the 
ordinates  of  curve  ' '  AB ' '  the  watts  required  to  exhaust  one  cubic 


FIG.    79. 


MODIFICATION    OF    RECIPROCATING    PUMP    MADE    BY    THE 
SANITARY    DEVICES    MANUFACTURING    COMPANY. 


foot  of  free  air.  Curve  "cd"  represents  the  theoretical  watts 
required  to  do  the  same  work.  These  compressors  were  used  iD 
connection  with  systems  operating  with  1-in.  hose  and  the 
vacuum  usually  carried  was  15  in.  mercury.  They  require  ap- 
proximately 77  watts  per  cubic  foot  of  free  air  at  this  vacuum 
and  the  efficiency,  shown  in  curve  "ee"  (Fig.  78)  is  46%. 

Were  this  compressor  used  in  connection  with  a  system  oper- 
ating through  1*4  -in.  hose  and  a  vacuum  of  8  in.  mercury  main- 
tained, the  efficiency  would  drop  to  31%. 

A  modification  of  the  reciprocating  pump  was  manufactured 
by  the  Sanitary  Devices  Manufacturing  Company  in  which 


VACUUM  PRODUCERS 


145 


light-weight  poppet  valves  placed  in  the  heads  of  the  cylinder 
were  used,  as  indicated  in  Fig.  79.  Curves  of  the  watts  per 
cubic  foot  and  efficiency  of  this  type  of  compressor  are  shown 
in  Fig.  80.  It  will  be  noted  that  this  compressor  shows  a  better 
efficiency  than  the  air  compressor  at  all  degrees  of  vacuum  and 
it  is  the  best  reciprocating  pump  that  the  writer  has  ever  tested. 
This  pump  was  made  for  several  years  without  water  jacket 
and  no  trouble  was  ever  experienced  with  overheating.  How- 
ever, owing  to  the  commercial  air  compressors  being  jacketed, 
the  makers  using  same  made  this  a  talking  point  and  this  com- 
pany was  obliged  to  jacket  its  pumps. 


<o  8  10 

Vacuum  Ins.  Mercury 

FIG.    80.      POWER    CONSUMPTION     AND     EFFICIENCY     OF     MODIFIED 
RECIPROCATING    PUMP. 

The  Vacuum  Cleaner  Company  used  a  Clayton  pump  on  its 
smaller  plants  which  was  fitted  with  a  semi-rotary  valve  in  each 
end  serving  as  an  induction  and  eduction  valve,  while  the  heavy 
poppet  eduction  valve  of  the  air  compressor  was  dispensed  with. 
The  increase  in  efficiency  that  should  have  resulted  from  this 
change  was  not  realized.  The  reason  for  this  can  be  more 
readily  seen  by  inspection  of  the  indicator  cards,  Figs.  81 
and  82. 

Fig.  81  is  a  card  taken  from  one  of  the  Clayton  compressors 
fitted  with  combined  induction  and  eduction  valves,  and  Fig. 
82  a  card  from  a  compressor  with  light  steel  induction  and 
eduction  valves  of  the  poppet  type. 


146  VACUUM    CLEANING    SYSTEMS 

It  will  be  noted  that  the  compression  line,  a-d,  Fig.  81,  ex- 
tends above  the  atmosphere  line,  the  pressure  at  the  time  of 
opening  the  eduction  valve  being  4  Ibs.  per  square  inch  above 
the  atmosphere.  This  is  due  to  tihe  failure  of  the  mechanically- 
operaited  valve  to  open  soon  enough.  This  valve  being  also  the 
induction  valve,  it  is  necessary  for  the  eduction  port  to  be  closed 
before  the  induction  port  can  be  opened,  in  order  to  prevent  a 
short  circuit  of  air  from  the  atmosphere  into  the  separators. 
This  fact  is  responsible  for  the  sudden  increase  in  the  pressure 
at  b,  the  eduction  port  having  closed  before  the  completion  of 
the  stroke  and  the  air  in  the  clearance  space  being  compressed 


A- 1.5 

Atm.     L-LI3 
MLP-705 


Abs. 


Atm 


!7"Vac 

A-1.7 
L-L54 
MEP-6.70 


FIGS.  81  AND  82.      INDICATOR   CARDS    FOR    CLAYTON  AND    MODIFIED 

PUMPS. 

to  6y2  Ibs.  above  atmosphere.  The  induction  port  is  not  opened 
until  after  the  beginning  of  the  suction  stroke  resulting  in  the 
high  degree  of  vacuum  at  c. 

Compare  this  with  the  card,  Pig.  82.  Here  the  compression 
does  not  extend  -above  the  atmosphere  line  more  than  %  Ib. 
per  square  inch  and  the  eduction  valve  does  not  close  until  the 
end  of  the  stroke  so  tlhat  the  vacuum  at  the  beginning  of  the 
suction  stroke  is  no  lower  than  during  the  entire  stroke. 

These  pumps  were  working  under  the  same  conditions,  i.  e., 
15-in.  vacuum  in  the  separator.  The  M.  E.  P.  for  Fig.  81  is 
7.05  while  that  in  Fig.  82  is  6.7  and  is  higher  than  is  usually 
the  case  with  this  pump,  due  to  the  fact  that  the  exhaust  pipe 


VACUUM  PRODUCERS  147 

from  this  pump  was  very  long  and  crooked,  a  condition  which 
should  be  avoided  whenever  possible.  Also,  the  pump  from 
which  this  card  was  taken  is  one  of  the  older  pattern  and  the 
clearance  was  greater  than  in  the  later  models.  The  point  at 
which  the  eduction -valve  opens  in  Fig.  81  is  53%  of  the  stroke 
and  it  closes  at  95%  of  the  stroke  and  is,  therefore,  open  42% 
of  the  stroke,  while  in  Fig.  82  the  eduction  valve  opens  ait  46% 
of  the  stroke  and  remains  open  to  the  end  of  the  stroke,  andv 
therefore,  is  open  for  54%  of  the  stroke.  Thus  the  pump  with 
the  poppet  valves  will  move  more  air  at  the  same  vacuum  with 
less  expenditure  of  power  than  the  pump  with  the  mechanically- 
operated  valves. 

Another  type  of  reciprocating  pump  has  been  introduced  in 
the  past  two  or  three  years  in  which  a  single  valve  which  ro- 
tates continuously  in  one  direction  is  used  for  induction  and 
eduction  valve,  for  both  ends  of  the  cylinder.  This  valve  is  a 
plain  cylindrical  casting  having  ports  cored  through  to  alter- 
nately connect  the  cjdinder  ports  with  the  intake  and  exhaust 
ports. 

By  rotating  this  valve  180°  on  its  stem  the  vacuum  pump 
is  changed  to  an  air  compressor.  This  arrangement  is  adopted 
in  order  to  discharge  the  contents  of  the  separator  into  the 
sewer  as  was  explained  in  Chapters  I  and  VIII.  In  this  pump 
there  must  be  points  at  which  both  the  induction  and  eduction 
valves  are  closed  at  the  same  time  and  results  similar  to  those 
found  with  the  semi-rotary  valves  of  the  Clayton  pump  will 
naturally  be  in  evidence.  The  author  has  endeavored  to  obtain 
an  indicator  card  from  one  of  these  pumps  but  has  been  un- 
able to  do  so.  The  effect  of  simultaneous  closing  of  both  in- 
duction and  eduction  ports  would  naturally  be  more  marked  in 
this  pump  than  in  the  Clayton,  as  the  motion  of  the  valve  in 
this  case  is  uniform  at  all  times  while  the  motion  of  the  valve 
gear  of  the  Clayton  pump  is  so  arranged  that  the  valve  moves 
very  fast  at  the  time  that  both  ports  are  closed.  One  of  the  two 
pumps  of  this  type  which  was  recently  installed  in  the  New 
York  Post  Office  is  illustrated  in  Fig.  83.  These  pumps  have 
a  displacement  of  1,200  cu.  ft.  each  and  are  the  largest  recip- 
rocating pumps  in  use  for  vacuum  cleaning  at  this  writing. 


148  VACUUM    CLEANING    SYSTEMS 

An  interesting  property  of  the  piston  pump  which  lends 
itself  to  the  economical  control  of  the  vacuum  in  the  system  is 
illustrated  by  the  curve  at  the  top  of  Fig.  78  which  shows  the 
total  power  required  to  operate  the  Clayton  type  air  com- 
pressor, the  efficiency  of  which  is  indicated  by  the  lower  curves 
on  this  figure.  The  compressor  was  operated  at  constant  speed 
and  the  air  volume  varied  to  give  various  degrees  of  vacuum 
from  atmospheric  pressure  to  a  closed  suction  and  the  power 
to  operate  the  compressor  read  at  intervals  of  two  inches.  The 
current  input  to  the  motor  in  amperes  is  indicated  by  ordinates 
and  the  vacuum  in  the  separator  by  the  abscissae.  This  indi- 
cates that  the  piston  pump  requires  the  maximum  power  to 


FIG.   83.      ONE   OF   THE  PUMPS   INSTALLED   IN  CONNECTION   WITH  THE 

VACUUM  CLEANING  SYSTEM  IN  THE  NEW  YORK  POST  OFFICE, 

THE  LARGEST  RECIPROCATING  PUMP  USED  FOR  THIS 

PURPOSE    UP    TO    THE    PRESENT. 

operate  at  about  15-in.  vacuum  and  that  the  least  power  is  re- 
quired when  the  vacuum  is  at  the  highest  point  possible  to  ob- 
tain. The  method  employed  in  utilizing  this  characteristic  of 
a  piston  pump  will  be  discussed  in  a  later  chapter. 

Rotary  Pumps. — The  Garden  City  rotary  pump  is  a  good 
example  of  the  single-impeller  type  of  pump  and  is  or  has 
been  used  to  some  extent  by  at  least  two  makers  of  vacuum 
cleaning  systems.  Its  interior  arrangement  is  shown  in  Fig. 
84.  A  solid  cylindrical  impeller,  A,  is  mounted  eccentrically  in 
the  cylindrical  outer  casing,  the  impeller  being  fitted  with  four 
sliding  vanes  which  are  provided  with  distance  pieces,  E,  and 


VACUUM  PRODUCERS 


149 


wearing  faces,  B.  The  oil  reservoir  is  provided  with  a  needle 
valve  which  is  automatically  opened  as  soon  as  there  is  any 
vacuum  produced  and  closes  automatically  when  the  machine  is 
shut  down.  The  rate  of  feed  of  oil  is  adjusted  by  the  screw  I. 
This  type  of -pump  offers  a  large  surface  in  rubbing  contact 
with  the  case  and  becomes  very  hot  when  in  operation.  It  re- 
quires liberal  lubrication  in  order  to  prevent  heating  and  cut- 
ting of  the  surface  of  the  casing.  End  wear  in  these  pumps 
causes  leakage,  and,  as  usually  constructed,  there  are  no  means 


FIG.  84.      INTERIOR  ARRANGEMENT  OF  THE  GARDEN  CITY  ROTARY   PUMP. 

provided  for  taking  up  this  wear.  It  can  be  provided  for, 
however,  by  using  metal  shins  on  the  ends  of  the  cylindrical 
casing. 

The  power  required  to  operate  this  type  of  pump  (Curve  a-b, 
Fig.  85),  is  nearly  the  same  as  that  required  to  operate  a  piston 
pump  for  vacuum  less  than  12  in.  mercury,  but  when  the  vacuum 
becomes  higher,  the  power  required  becomes  much  greater  than 
that  required  by  the  piston  pump.  The  efficiency  (Curve  c-e, 
Fig.  85),  is  identical  with  that  obtained  with  the  light- weight 
poppet  valve  pump  (Curve  c-e,  Fig.  80)  from  0  to  11  in. 
vacuum,  but  for  higher  vacuum  the  efficiency  of  this  type  of 


150 


VACUUM    CLEANING    SYSTEMS 


pump  falls  off,  while  the  efficiency  of  the  piston  pump  becomes 
greater  as  the  vacuum  becomes  higher.  This  difference  in  the 
characteristics  of  the  two  types  of  pumps  is  due  to  the  presence 
of  valves  in  one  case  and  their  absence  in  the  other.  With  the 
piston  pump  the  atmospheric  pressure  reaches  the  cylinder 
only  while  air  is  being  discharged,  the  eduction  valves  being 
closed  at  other  times  and  a  partial  vacuum  exists  on  both  sides 
of  the  piston.  The  higher  the  vacuum  produced,  the  less  time 
there  is  atmospheric  pressure  on  the  piston  until,  when  no  air 


140 


120 


100 


§ 


80 


'I 
o 

1.60 


FIG.  85. 


fc  6  10  12 

Vacuum  Ins.  Mercury 

POWER  REQUIRED  TO  OPERATE  GARDEN  CITY  TYPE  OF 
ROTARY  PUMP. 


is  discharged,  the  air  contained  in  the  clearance  space  of  the 
cylinder  is  compressed  and  expanded,  the  compression  and 
expansion  lines  being  coincident.  The  indicator  card  will  have 
no  area,  and  the  only  power  expended  is  that  required  to  over- 
come the  friction  in  the  moving  parts.  With  the  rotary  pump 
there  are  no  discharge  valves  to  hold  the  atmospheric  pressure 
from  the  discharge  side  of  the  impeller  and  the  compression  of 
the  rarified  air  is  accomplished  by  the  atmospheric  pressure 
admitting  air  through  the  eduction  port  into  the  chamber.  As 


VACUUM  PRODUCERS 


151 


it  comes  opposite  the  eduction  port  there  is  no  difference  in  the 
time  during  which  the  impeller  is  subject  to  atmospheric  pres- 
sure, no  matter  what  the  quantity  of  air  being  discharged.  The 

higher  the  vacuum  in  the 
spaces  containing  rarified  air, 
the  greater  the  difference  in 
pressure  on  the  opposite 
sides  of  the  sliding  vane  and, 
therefore,  the  greater  total 
power  required  to  turn  the 
rotor. 

Another  type  of  rotary 
pump  which  is  fast  becoming 
the  most  popular  is  the 
double-impeller  type.  This  is 
generally  known  as  the  Root 
blower,  as  the  firm  of  this 
name  was  the  first  to  manu- 
facture same.  They  have 
been  in  use  for  many  years 
as  blowers  for  gas  works,  and 
as  vacuum  producers  for 
various  purposes,  mainly  the 
operation  of  pneumatic  tube 
systems. 

Why  this  form  of  vacuum 
producer  was  not  earlier 
adopted  in  vacuum  cleaning 
systems,  instead  of  the  slid- 
ing-vane  type,  is  hard  to 
understand.  This  pump  con- 
tains two  impellers  or  cams 
which  are  mounted  on  shafts 
geared  together  and  revolve 
in  opposite  directions  inside 
of  a  case,  always  being  in 
close  proximity  to  the  case  and  to  each  other,  but  never  touching. 
They  are,  therefore,  frictionless  in  operation  and  the  introduc- 


FIG.  86.  ARRANGEMENT  OF 
DOUBLE-IMPELLER  ROOT  TYPE 
ROTARY  PUMP  FOR  VACUUM 
CLEANING  WORK. 


152  VACUUM    CLEANING    SYSTEMS 

tion  of  a  small  amount  of  water  renders  them  practically  air 
tight.  There  being  no  metallic  contact  between  the  moving 
parts,  internal  lubrication  is  unnecessary  and  there  is  no  wear 
on  either  the  impellers  or  the  casing  and  no  means  of  taking 
up  wear  are  necessary. 

The  arrangement  of  the  impellers  and  the  method  of  provid- 
ing water  to  seal  the  parts  is  shown  in  Fig.  86.  A  reservoir 
containing  water  is  provided  on  the  discharge  side  of  the  pump 
and  a  small  pipe  leads  from  this  reservoir  to  the  suction  side  of 
the  pump.  The  vacuum  lifts  water  from  the  reservoir  and  dis- 
charges same  in  a  spray  into  the  suction  chamber.  This  water 
passes  through  the  pump  and  is  separated  from  the  air  in  the 
discharge  chamber  to  be  returned  to  the  suction  chamber  by  the 


FIG.  87.   ROTARY  PUMP  ARRANGED  WITH  DOUBLE-THROW  SWITCH 
FOR  REVERSING  PUMP. 

vacuum.  This  operation  will  start  automatically  as  soon  as  any 
degree  of  vacuum  is  formed  and  will  cease  as  soon  as  the  pump 
is  shut  down. 

Any  of  these  rotary  pumps  having  no  valves  can  be  changed 
to  an  air  compressor  by  reversing  the  direction  of  rotation. 
This  is  adapted  by  the  American  Rotary  Valve  Company  in 
connection  with  their  wet  separators  to  discharge  the  contents 
of  the  separator  into  the  sewer,  on  all  of  their  smaller-sized 
plants.  Fig.  87  shows  one  of  these  plants  arranged  with  double- 
throw  switch  for  reversing  the  electric  motor  used  to  operate 
the  pump  and  also  shows  the  arrangement  of  the  rotary  brush 


VACUUM  PRODUCERS 


153 


which  is  used  to  clean  the  screen  in  the  wet  separator,  as  has 
been  explained  in  Chapter  VIII. 

The  power  consumption  and  efficiency  of  this  type  of  pump 
are  shown  in  Fig.  88.     The  watts  per  cubic  foot  of  free  air 


rao 

130 

izo 
no 

t;ioo 
*eo 

I  ao 

o 

8.70 
I  6° 

^  50 

40 
30 
ZO 
10 


<o  &  10 

Vacuum  Ins.  Mercury 


Ifc 


FIG.  88.      POWER  CONSUMPTION  AND  EFFICIENCY  ROOT  TYPE  OF  PUMP. 

(Curve  a-b)  show  a  much  lower  consumption  of  power  at  the 
lower  vacuum  than  any  of  the  pumps  already  tested.  This  is 
probably  due  to  thej  fact  there  is  no  internal  friction.  It  will 


FIG.  89.   THE  ROTREX  VACUUM  PUMP,   USED   BY  THE  VACUUM 
ENGINEERING  COMPANY. 


154 


VACUUM    CLEANING    SYSTEMS 


be  noted  that  the  power  to  operate  at  no  vacuum  is  but  10 
watts  per  cubic  foot  of  free  air,  while  all  the  others  require 
from  24  to  34  cubic  feet.  This  also  results  in  the  efficiency 
curve  (c-e,  Fig.  88)  reaching  its  maximum  value  at  a  lower 
vacuum  than  in  the  case  of  the  sliding  vane  pump  (Fig.  85). 
The  efficiency  is  fairly  constant  between  6-in.  and  10-in. 


FIG.    90.      LATE   TYPE    OP   CENTRIFUGAL   EXHAUSTER   MADE    BY    THE 
SPENCER    TURBINE    CLEANER    COMPANY. 

vacuum  and  is  much  higher  than  is  obtained  with  any  of  the 
other  types  of  pumps  at  these  vacua.  When  they  are  operated 
at  higher  vacuum  the  efficiency  is  about  the  same  as  obtained 
with  the  sliding  vane  pumps  and  lower  than  that  obtained  with 
the  reciprocating  pumps.  The  best  efficiency  of  this  pump  is 
at  the  vacuum  necessary  to  operate  a  cleaning  system  provided 
with  1^4 -in.  hose. 

A  slight  modification  of  this  type  of  pump  is  that  used  by  the 
Vacuum  Engineering   Company,   known  as  the  Rotrex.     This 


VACUUM  PRODUCERS 


155 


pump  has  but  one  impeller,  of  nearly  the  same  form  as  the 
impellers  in  the  Root  blowers  and  has  a  follower  driven  by 
crank  and  connecting  rods  which  is  always  in  close  proximity 
to  the  impeller  but  does  not  touch  same.  The  arrangement  of 


10    100 
9      90 


70 


5      50 

A  i*  40 

E 

3  §  50 
2-^20 


Cubic  Foot  of  Air  p«r  Minu+e 


400 


500 


FIG.    91.      POWER    AND    EFFICIENCY    CURVES    FOR    THE    SPENCER 

MACHINE. 

this  pump  is  illustrated  in  Fig.  89  which  also  shows  the  satura- 
tion chamber  and  screens  used  instead  of  a  separator,  as  ex- 
plained in  Chapter  VIII. 

The  author  has  never  tested  the  economy  of  these  pumps  but 
would  infer  that  their  economy  should  be  about  the  same  as 
that  of  the  Root  blower. 

Centrifugal  Exhausters. — This  type  of  exhauster  has  always 
taken  the  form  of  a  fan.  The  first  stationary  fan  type  of  ex- 
hauster was  manufactured  by  the  Spencer  Turbine  Cleaner 
Company.  Their  latest  type  is  illustrated  in  Fig.  90.  It  con- 
sists of  a  series  of  centrifugal  fans  mounted  on  a  vertical  shaft, 
stationary  deflection  blades  being  provided  between  the  wheels 


156 


VACUUM    CLEANING    SYSTEMS 


to  conduct   the  air   from   the  periphery   of   one  wheel   to   the 
center  of  the  next. 

These  centrifugal  exhausters  do  not  have  a  positive  displace- 
ment, as  do  all  those  already  described,  and  therefore  the  varia- 
tion of  the  vacuum  is  not  as  much  as  in  case  of  the  positive 
displacement  machines.  The  vacuum  produced  when  the  ma- 
chine is  moving  no  air  is  slightly  less  than  the  maximum  that 


FIG.  92.      INTERIOR  ARRANGEMENT  OF  INVINCIBLE  MACHINE,  MANU- 
FACTURED    BY    THE     ELECTRIC     RENOVATOR     MANU- 
FACTURING  COMPANY. 

the  exhauster  can  produce  and  there  is  very  little  variation  in 
the  vacuum  with  air  quantities  which  can  be  moved  without 
exceeding  the  capacity  of  the  motor  or  other  means  producing 
the  power.  The  curves  showing  the  power  required  to  operate 


VACUUM  PRODUCERS 


157 


and  the  efficiency  of  this  type  of  vacuum  producer  are,  there- 
fore, plotted  with  abscissae  representing  the  lair  moved  in 
cubic  feet  per  minute.  The  vacuum  produced  and  the  power 
required  to  operate  are  plotted  as  ordinates.  The  curves  for 
the  Spencer  machine  are  shown  in  Fig.  91.  This  curve  is  taken 
from  a  four-sweeper  machine  and  the  vertical  lines  numbered 


100  ZOO  300  400 

Cu  Ft  Atmos.Air  per  Minute 


FIG.  93.      POWER  CONSUMPTION.  VACUUM  AND  EFFICIENCY  OF  FIRST 
TYPES   OF   INVINCIBLE   MACHINE. 

1  to  4  represent  the  conditions  when  that  number  of  sweepers 
are  in  operation;  that  is,  bare  floor  renovators,  with  50  ft. 
of  hose  or  80  cu.  ft.  of  free  air  per  minute.  The  maximum 
efficiency  is  reached  at  full  load  and  is  'approximately  42%. 
The  vacuum  at  this  efficiency  is  5^  in.  mercury,  a  drop  of  ^4-in. 
from  the  maximum  which  was  obtained  at  one-fourth  load. 

These  machines  have  rather  large  clearances  and  a  prelimi- 
nary separator  is  all  that  is  required.  They  operate  at  a  speed 
of  about  3,600  R.  P.  M.  and  the  peripheral  speed  of  the  fans 
varies  from  15,000  to  22,000  ft.  per  minute.  This  produces 


158 


VACUUM    CLEANING    SYSTEMS 


some  noise  and  considerable  vibration  and  care  must  be  exer- 
cised in  mounting  the  machine.  In  order  to  insure  quiet  run- 
ning the  usual  method  is  to  place  the  machine  on  a  felt  pad 
of  considerable  thickness. 

The  machines  made  by  the  Electric  Renovator  Manufactur- 
ing Company  are  horizontal  and  have  much  smaller  clearances 
than  the  Spencer  machines.  They  operate  at  approximately 
the  same  rotary  and  peripheral  speed  and  are,  therefore,  a& 


II  110 
10  100 
9  1*90 


100  200  300          400 

Cu  Ft  Atmos.Air  per  Mrnuie 


500 


FIG.    94. 


POWER    CONSUMPTION,    VACUUM    AND    EFFICIENCY    OF 
VINCIBLE    MACHINE    AFTER    VALVE    WAS    FITTED 
TO    DISCHARGE. 


noisy.  However,  the  center  of  gravity  of  tihese  machines  is. 
lower  and  the  vibration  is  not  so  great.  The  Spencer  Company 
is  now  making  a  horizontal  machine  which  it  furnishes  only 
when  required,  the  claim  for  their  vertical  machine  being  that 
the  weight  of  the  moving  parts  counteracts  the  thrust  of  the 
atmospheric  pressure  against  the  fans  and  relieves  the  work  of 
the  thrust  bearings,  at  the  expense  of  greater  vibration.  With 
ball  bearing  thrusts,  the  author  does  not  consider  this  to  be  of" 
great  importance. 


VACUUM  PRODUCERS 


159 


A  view  of  the  interior  arrangement  of  the  Invincible  machine, 
as  manufactured  by  tftie  Electric  Renovator  Manufacturing 
Company,  is  shown  in  Fig.  92. 

These  machines,  when  first  made,  were  without  valves  and 
the  power  consumption,  vacuum  and  efficiency  are  shown  in 
Fig.  93.  It  will  be  noted  that  the  vacuum  produced,  when  the 
machine  is  operated  at  or  below  one-half  load,  is  considerably 
lower  than  is  obtained  at  greater  loads.  This  characteristic 


FIG.     95.      FCfUR-SWEEPER    INVINCIBLE     PLANT     INSTALLED     IN    THE 
UNITED    STATES    POST-OFFICE   AT    LOS   ANGELES,    CAL. 

produces  a  disagreeable  noise  when  the  machine  is  not  handling 
any  air,  evidently  due  to  air  rushing  back  through  the  outlet 
when  the  vacuum  tends  to  build  up  to  the  maximum  which 
occurs  at  intervals  of  about  one-half  second. 

In  order  to  overcome  this  trouble  a  valve  has  been  fitted  to 
the  discharge,  as  indicated  at  4,  Fig.  92.  With  this  valve  in 
place  the  power  consumption,  efficiency  and  vacuum  are  as 


160  VACUUM    CLEANING    SYSTEMS 

shown  in  Fig.  94.  It  will  be  noted  that  the  vacuum  is  as  high 
at  no  load  as  at  any  load  up  to  full  load  and  is  practically 
constant.  The  efficiency  at  light  loads  is  the  same  as  before  but 
it  is  slightly  lower  at  full  load,  being  50%  without  the  valve 
and  4:7%  with  the  valve.  This  is  due  to  the  power  being  ex- 
pended in  opening  the  valve  for  large  quantities  of  air  and  to 
friction  in  the  valve  passage. 

A  four-sweeper  plant  of  this  manufacture  is  shown  in  Fig. 
95.  This  plant  is  installed  in  the  United  States  Post  Office 
at  Los  Angeles,  Cal.  The  separate  centrifugal  separator, 
shown  at  the  left  of  the  cut,  is  not  used  in  the  regular  equip- 
ment and  was  added  in  this  case  to  fullfil  the  specification  re- 
quirements. 

A  centrifugal  pump  with  a  single  impeller  is  manufactured 
by  The  United  Electric  Company  and  is  known  as  the  Tuec 
system.  A  phantom  view  of  the  pump  and  separator  is  shown 
in  Fig.  96.  It  will  be  noted  that  the  shaft  is  vertical.  How- 
ever, the  vacuum  is  under  the  impeller  in  this  case,  and  the 
thrust  due  to  the  atmospheric  pressure  is  down  instead  of  up, 
as  in  the  case  of  the  Spencer  machines.  This  throws  the  weight 
of  the  parts,  plus  the  thrust  due  to  atmospheric  pressure,  on 
the  thrust  bearing.  These  machines  do  not  produce  a  vacuum 
greater  than  3-in.  mercury,  and  the  additional  thrust  is  not  as 
great  as  in  the  case  of  the  machines  producing  higher  vacuum, 
the  impeller  being  24  in.  in  diameter,  its  area  450  sq.  in.  and 
the  thrust,  with  a  vacuum  of  3-in.  mercury,  675  Ibs.,  which 
is  worth  considering.  This  downward  thrust  is  partially  coun- 
terbalanced by  mounting  the  armature  of  the  electric  motor 
used  to  operate  the  fan,  slightly  below  the  magnetic  center, 
thereby  causing  an  upward  magnetic  pull.  These  machines  are 
intended  to  be  used  with  large  hose  and  pipe  lines  to  reduce 
the  friction  to  a  very  low  point.  When  operating  carpet  reno- 
vators the  vacuum  at  the  renovator  rises  to  1^4 -in.  mercury  and 
the  type  of  renovator  used  by  them  passes  approximately  50 
cu.  ft.  of  air,  while  the  bare  floor  renovators  pass  approximately 
95  cu.  ft.  They  are  extensively  used  -where  bare  floor  work 
is  required,  their  first  cost  being  low. 

The  results  of  tests  of  two  of  these  machines  of  four-sweeper 
capacity,  driven  by  alternating  and  direct-current  motors, 


VACUUM  PRODUCERS 


161 


respectively,  are  shown  in  Fig.  96a.  These  curves  indicate  a 
considerably  higher  efficiency  with  the  alternating  than  with 
the  direct-current  motor.  This  is  due  to  the  low  efficiency  of 
the  special  high-speed  direct-current  motors  used  with  all  centri- 


FIG.     96.      CENTRIFUGAL     PUMP     WITH     SINGLE     IMPELLER,     MANU- 
FACTURED   BY    THE    UNITED    ELECTRIC    COMPANY. 

fugal  fan-type  exhausters.     The  alternating-current  motors  are 
not  so   affected,   in   fact,   the   speed   at  which   these   fans   are 
operated  is  fixed  by  the  requirements  of  the  alternating-current 
motors. 
The  efficiency  of  the  other  types  of  centrifugal  exhausters 


162 


VACUUM    CLEANING    SYSTEMS 


(Figs.  91,  93  and  94)  is  in  every  case  accomplished  with  direct- 
current  motors.  This  machine  has  an  efficiency  about  the  same 
as  the  Spencer  machine.  It  will  noted  that  the  vacuum  produced 
does  not  fall  off  as  the  load  increases,  as  in  the  case  of  the  multi- 
stage fans.  This  characteristic  is  probably  due  to  the  fact  that 
there  is  no  wire  drawing  in  the  diversion  vanes,  as  in  the  case  of 
the  multi-stage  exhauster. 


6      6      60 


0      0 


500 


0  100  200  300  400 

Free  Air  per  Minute,  Cubic  Feet 

FIG.    96a.      TEST    OF    CENTRIFUGAL    PUMP    WITH    SINGLE    IMPELLER 


Steam  Aspirators.—  The  steam  aspirator  as  a  vacuum  pro- 
ducer in  connection  with  vacuum  cleaning  systems  was  first  used 
hy  the  American  Air  Cleaning  Company,  and  has  been  used 
to  a  limited  extent  by  the  Sanitary  Devices  Manufacturing  Com- 
pany. The  type  of  apparatus  used  by  the  American  Air  Cleaning 
Company  is  illustrated  in  Fig.  97.  A  single  partial  separator  is 
used  with  this  system  and  the  lighter  dust  is  allowed  to  pass 


VACUUM  PRODUCERS 


163 


through  the  aspirator,  where  it  is  mixed  with  the  steam  and 
sterilized.  The  aspirator  is  in  the  form  of  an  ejector,  with  a 
specially  designed  nozzle,  and  is  always  fitted  with  an  automatic 
device  for  cutting  off  the  steam  when  the  vacuum  in  the  sepa- 
rator reaches  the  degree  desired. 

The  steam  consumption  required  to  exhaust  1  cu.  ft.  of 
free  air  at  various  vacua,  as  determined  by  actual  test  of  four 
different  nozzles,  is  shown  in  Fig.  98,  the  steam  being  the  actual 
weight  of  dry  and  saturated  steam  at  the  gauge  pressures  noted. 


Vacuum  Pipe 
{((.leaning  Maine) 


,  Exhausf  fo  5fack 
5 


FIG.    97.      STEAM    ASPIRATOR    USED    BY    THE    AMERICAN    AIR    CLEAN- 
ING COMPANY. 

The  American  Air  Cleaning  Company  used  to  guarantee  a 
steam  consumption  of  250  Ibs.  per  hour  from  and  at  212°  F., 
assuming  that  the  feed  water  temperature  was  32°  F.,  the 
vacuum  to  be  maintained  at  9  in.  mercury  at  the  aspirator. 

Taking  the  results  of  the  test  of  the  three-sweeper  nozzle  as 
an  average,  0.066  Ibs.  of  steam  will  be  required  to  exhaust  1 
cu.  ft.  of  free  air  at  9  in.  vacuum.  The  total  heat  in  1  pound 
of  dry  steam  at  110  Ibs.'  gauge  is  1187  B.  T.  U.  and  at 


164 


VACUUM    CLEANING    SYSTEMS 


212°  F.  the  latent  heat  is  970  B.  T.  U.  The  factor  of 
evaporation,  therefore,  is  1.235,  and  the  weight  of  steam  at  110 
Ibs.  allowed  by  the  guarantee  is  202  Ibs.  This  amount  of  steam 
will  exhaust  3,060  cu.  ft.  per  hour,  or  51  cu.  ft.  per  minute, 
which  is  more  than  sufficient  to  operate  a  carpet  renovator,  and 
is  a  little  less  than  will  pass  through  a  bare  floor  brush  attached 
to  the  end  of  50  ft.  of  1  in.  diameter  hose,  if  the  hose  is 
attached  directly  to  the  aspirator.  With  a  line  of  pipe  between 


-06 


IZ  14 

Vacuum  Ins  Mercury 


FIG.  98.      STEAM   CONSUMPTION  OF  STEAM  ASPIRATOR. 


the  hose  cock  and  the  aspirator,  the  air  quantity  will  be  some- 
what less,  and  this  guarantee  will  undoubtedly  be  fulfilled  in 
every  case. 

The  advisability  of  using  an  aspirator  will  depend  on  tho 
conditions  to  be  met  at  the  building  in  each  case.  Three  typical 
cases  are  cited  below: 

i.  When  there  is  a  Generating  Plant  in  the  Building,  and 
a  Plant  Using  i^-in.  Hose  and  8-in.  Vacuum  is  Desired.— 
A  Root  blower  will  require  27  watts  for  each  cubic  foot  of  air 
exhausted  (Fig.  88),  and  the  three-sweeper  aspirator,  0.065 


VACUUM  PRODUCERS  165 

Ibs.  of  steam.  Then  the  pounds  of  steam  required  by  the 
aspirator  to  do  the  same  work  as  one  K.  W.  hour  at  the  motor 
of  the  Root  blower  will  be 

o-o65X6o          6 

0.027 

The  generating  plant  will  produce  a  kilowatt  hour  at  the  switch- 
board with  not  exceeding  60  Ibs.  of  steam,  and  if  the  trans- 
mission loss  is  10%  there  will  be  required  by  the  Root  blower 
not  over  66  Ibs.  of  steam  to  do  the  same  work  that  takes  146 
Ibs.  with  the  aspirator.  This  case  would  require  that  the  Root 
blower,  driven  by  an  electric  motor,  be  used. 

2.  When  there  is  High  Pressure  Steam  Available,  but  no 
Generating  Plant. —  Then  we- may  use  either  the  aspirator  or 
a  Root  blower  driven  by  a  steam  engine.     This  engine  should 
have  an  economy  of  60  Ibs.  per  indicated  horse  power,  with  not 
over  15%   friction  loss,  which  will  require  69  Ibs.  per  brake 
horse  power.     This  will  be  equivalent  to  69X0.776=90^  Ibs. 
per  K.  W.  hour,  which  is  still  much  better  than  146  Ibs.  required 
by  the  aspirator. 

3.  When  Steam  is  Generated  on  the  Premises  with  Coal 
Costing  $3.00  per  ton  and  all  Machinery  Must  be  Driven  by 
Electricity  Purchased  for  5  Cents  per  K.  W.  Hour. — Cost  of 
steam  to  do  the  same  work  in  the  aspirator  that  1  K.  W.  hour 
will  do  in  a  motor  driving  a  Root  blower  is: 

146X300        0 
7,     ° — =2.8  cents 
7X2240 

as  against  5  cents  that  would  have  to  be  paid  for  current.  In 
this  case  there  would  be  a  saving  in  using  the  aspirator,  which 
would  not  require  as  much  attention  as  the  motor,  and  at  loads 
less  than  full  load,  the  steam  used  by  the  aspirator  would  be 
in  direct  proportion  to  the  load,  as  the  control  would  shut  the 
steam  off  entirely  during  a  portion  of  the  time,  while  the  motor 
would  require  some  current  as  long  as  it  was  in  operation,  even 
if  no  air  was  being  exhausted.  On  the  other  hand,  the  steam 
which  is  exhausted  from  the  aspirator  is  not  suitable  for  use 
in  heating,  as  it  is  mixed  with  air  and  fine  dirt,  and  must  be 
thrown  away,  a  condition  that  must  always  be  considered  where 
there  is  an  opportunity  to  use  exhaust  steam  for  heating  or 
other  purposes. 


CHAPTER  X. 
CONTROL. 

When  the  displacement  type  of  vacuum  producer  of  more 
than  one-sweeper  capacity  is  used  with  a  vacuum  cleaning 
system,  some  means  must  be  employed  to  prevent  the  vacuum 
rising  above  that  necessary  for  efficient  operation  of  the  sweepers 
when  there  are  less  renovators  in  use  than  the  capacity  of  the 
vacuum  producer  or  when  carpet  renovators  are  in  use  on  all 
outlets. 

If  the  displacement  pump  be  run  -at  constant  speed,  every 
change  in  the  quantity  of  air  exhausted  will  cause  a  change 
in  the  vacuum  produced.  This  will  result  in  inefficient  opera- 
tion and  may  result  in  undue  effort  being  necessary  to  operate 
the  renovator  and  in  excessive  wear  on  the  carpets. 

The  earlier  systems  were  not  provided  with  any  control  and 
the  first  'attempt  to  control  the  vacuum  was  by  placing  a  spring 
relief  valve  on  the  pipe  line  near  the  separator,  which  admitted 
additional  air  when  the  vacuum  tended  to  rise.  This  resulted 
in  full  load  being  thrown  on  the  pump  at  all  times  when  the 
same  was  in  use,  which  does  not  give  economical  operation. 

The  controllers  that  have  been  devised  for  maintaining  a 
constant  vacuum  without  the  introduction  of  air  into  the 
system  operate  on  one  of  three  principles : 

1.  Closing  the  suction  of  the  vacuum  producer. 

2.  Opening  the  suction  of  the  vacuum  producer  and  holding 
vacuum  in  the  system. 

3.  Varying  the  speed  of  the  vacuum  producer. 

The  first  type  of  controller  was  introduced  in  the  vacuum 
cleaning  field  by  the  Sanitary  Devices  Manufacturing  Company, 
and  was  known  as  the  "unloading  valve."  It  was  similar  to 
the  unloader  which  had  been  used  for  some  time  in  connection 
with  air  compressors.  The  detail  of  construction  is  shown  in 
Fig.  99,  and  consists  of  a  balanced  valve,  which  is  con- 

166 


CONTROL 


167 


nected  to  a  weighted  piston,  operating  in  a  chamber  com- 
municating with  the  separators  by  a  pilot  valve.  The  pilot 
valve  is  operated  by  an  auxiliary  piston  which  is  weighted 
to  overcome  the  lifting  effort  due  to  the  vacuum  desired. 

When  the  vacuum  in  the  cylinder 
becomes  great  enough  to  overcome 
the  weights  attached  to  the  aux- 
iliary piston,  it  rises,  allowing 
vacuum  to  reach  the  main  piston, 
which  is  drawn  up  and  the  suc- 
tion valve  closed.  When  this  valve 
is  closed  the  vacuum  in  the  pump 
at  once  starts  to  build  up  to  the 
maximum  possible  for  the  pump 
to  produce,  and  if  the  pump  used 
is  of  the  piston  type  the  vacuum 
will  run  up  to  nearly  28  in.,  re- 
sulting in  the  pump's  taking  the 
least  power  on  which  it  can  be 
operated.  As  soon  as  the  vacuum 
in  the  separators  falls  below  that 
which  will  sustain  the  weight  on 
the  auxiliary  piston  the  valve  falls 
open  and  the  pump  again  draws 
air  through  the  system.  In  actual 
practice  this  valve  will  operate  at 
more  or  less  frequent  intervals. 
The  author  timed  the  action  of 
one  of  these  valves  connected  to 
of  «  eight-deeper 


TURING    COMPANY,    KNOWN    AS     f  3/5 

THE    "UNLOADING   VALVE." 


SANITARY  DEVICES  MANUFAC-  piston  pump,  and  its  time  varied 

OVid     to     65     seCOnds. 

The  current  taken  by  the  pump 
when  the  suction  was  open  was  100  amperes  at  220  volts.  When 
the  valve  was  closed  for  but  2/5  second  the  current  dropped  to 
75  amperes,  there  not  being  sufficient  elapsed  time  for  the  pump 
to  produce  a  perfect  vacuum.  When  the  valve  was  closed  for 


168 


VACUUM    CLEANING    SYSTEMS 


2  1/6  seconds,  the  vacuum  reached  its  maximum  value  and  the 
current  fell  to  32  amperes. 

Fig.  100  is  a  curve  plotted  from  the  results  of  this  test 
and  shows  an  increase  in  the  power  above  that  necessary  to 
overcome  the  friction  in  the  moving  parts  of  the  pump  in 
direct  proportion  to  the  percentage  of  full  load  that  the  pump 
was  serving. 

This  is  as  near  an  ideal  condition  as  one  could  expect  to 
obtain  by  any  means  other  than  stopping  the  pump  or  other- 
wise decreasing  the  friction  load.  However,  this  form  of 


100 


T3 
O 
o 


•s 

540 

k. 
07 


01  t  3  4  5678 

Sweepers  in  Use 

FIG.    100.      TEST    OF  CONTROLLER     CONNECTED     TO     SUCTION     OF 
8-SWEEPER    PISTON   PUMP. 

unloader  is  not  suitable  for  a  pump  without  valves,  as  the 
power  will  increase  with  an  increase  in  vacuum,  and  other 
means  must  be  employed  to  control  such  a  pump. 

The  second  form  of  control  is  adapted  to  this  type  of  pump. 
The  arrangement  of  one  of  these  controls  is  shown  in  Fig.  101. 
This  consists  of  a  single-ported  valve  opened  by  the  vacuum 
in  the  cylinder,  M,  the  action  of  which  is  controlled  by  a  pilot 
or  auxiliary  control  valve  actuated  by  the  vacuum  in  the  sep- 
arator. This  auxiliary  valve  is  fitted  with  two  pistons,  S  and 


CONTROL 


169 


O,  which  are  held  together  by  springs,  and  when  so  held  the 
main  cylinder  is  open  to  the  atmosphere  through  the  small 
ports  in  the  piston,  0.  When  the  vacuum  in  the  separator 
becomes  great  enough  to  overcome  the  compressive  strength  of 
the  springs,  T  and  P,  the  pistons,  S  and  0,  are  drawn  apart, 
closing  the  port  in  the  piston,  0,  and  opening  the  port  in  piston, 
S,  allowing  the  vacuum  to  enter  the  main  cylinder,  M,  and 
open  the  main  valve.  This  valve  permits  the  atmospheric 
pressure  to  enter  the  pump  suction,  the  air  being  prevented 
from  entering  the  separators  by  a  check  valve,  not  shown.  The 
pump  then  operates  without  producing  any  vacuum,  and  the 


FIG.  101. 


TYPE  OF  CONTROLLER  FOR  USE  ON  PUMPS  WITHOUT 
VALVES. 


power  required  to  operate  the  pump  is  reduced.  A  relief  valve 
of  the  common  vacuum-breaker  type  is  shown  at  the  left  of 
the  cut.  This  valve  is  provided  to  prevent  overload  in  case  the 
control  fails  to  operate. 

This  type  of  control  does  not  effect  as  great  a  reduction  in 
the  power  as  the  first  type  of  control  described,  since  it  requires 
a  greater  per  cent,  of  the  full  load  power  to  operate  the  pump 
at  no  vacuum  than  at  perfect  vacuum.  No  air  is  moved  in  the 
latter  case,  and  the  maximum  volume  of  air  is  moved  in  the 
former  case. 

Either  of  these  controls  gives  fairly  economical  results  when 


170 


VACUUM    CLEANING    SYSTEMS 


the  pump  is  serving  at  least  a  part  of  the  sweepers  at  all  times. 
However,  when  the  system  is  used  in  a  building  where  there 
may  be  cleaning  done  at  any  time  and  vacuum  must  be  "on 
tap ' '  at  all  times,  as  in  a  hotel,  there  will  be  many  occasions  when 
no  sweepers  will  be  in  use,  and  the  pump  might  then  be  stopped 
entirely,  provided  that  it  could  be  automatically  started  when 
needed. 


FIG.    102.      REGULATOR    FOR    MOTOR-DRIVEN    VACUUM    PUMP,    MANU- 
FACTURED BY  THE  CUTLER-HAMMER  MANUFACTURING  CO. 

• 

Where  the  steam  aspirator  is  used,  the  control  (Fig.  3&r)  is 
attached  to  the  steam  supply  valve.  When  the  valve  is  closed 
no  steam  is  consumed  by  the  aspirator.  This  is  the  ideal  con- 
dition where  we  must  keep  vacuum  "on  tap,"  and  is  a  char- 
acteristic of  the  aspirator  system  which  has  led  to  its  intro- 
duction in  many  instances. 


CONTROL  171 

The  same  economy  can  be  obtained  with  a  steam-driven 
pump  by  inserting  a  throttle  valve,  controlled  by  the  vacuum 
in  the  separators,  which  will  start  and  stop  the  engine  driving 
the  pump  and  vary  its  speed  in  accordance  with  the  quantity 
of  air  required  by  the  system. 

Several  appliances  for  varying  the  speed  of  a  motor-driven 
vacuum  pump  have  been  placed  on  the  market,  the  simplest 
and  probably  the  best  of  these  appliances  being  that  manu- 
factured by  the  Cutler  Hammer  Manufacturing  Company,  illus- 
trated in  Figs.  102  and  103. 

The  object  of  the  apparatus  shown  in  Fig.  102  is  to  auto- 
matically start  a  motor-driven  vacuum  pump  and  control  the 


FIG.    103.        INSPIRATOR   TYPE   VACUUM    CONTACTOR,   USED   TO  CONTROL 
PILOT   MOTOR   OF    CUTLER -HAMMER    CONTROLLER. 

speed  of  the  motor  so  that  the  vacuum  is  maintained  at  the 
desired  degree,  irrespective  of  variation  in  the  number  of 
sweepers  in  use.  This  control  of  the  degree  of  variation  is 
accomplished  in  a  more  efficient  manner  than  if  the  pump  were 
to  be  driven  at  its  maximum  speed  at  all  times  and  the  pressure 
kept  at  the  desired  point  by  means  of  a  blow-off  or  by-pass 
valve.  'With  this  system  a  motor  is  used  having  a  control,  by 
shunt  field  weakening,  of  approximately  3  :1  in  order  that  the 
control  of  the  speed  may  be  as  efficient  as  possible. 

Referring    to    Fig.    103,    a    small    pilot    motor    is    mounted 


172  VACUUM    CLEANING    SYSTEMS 

on  brackets  at  the  side  of  the  panel,  driving  directly,  through 
an  insulating  coupling,  a  screw  shaft  which  carries  a  traveling 
cross-head.  This  cross-head  is  shown  in  the  photograph  at  the 
extreme  right  of  its  travel,  which  corresponds  to  the  maximum 
speed  of  the  motor,  the  left-hand  end  corresponding  to  zero 
speed  of  the  motor.  In  this  position  the  motor  circuit  is  opened 
by  the  clapper  type  magnetic  switch.  Assuming  that  the  cross- 
head  is  in  the  extreme  left-hand  position  and  the  knife  switch 
is  closed,  the  pilot  motor  will  be  started  in  such  a  direction  as 
to  move  the  cross-head  to  the  right  A  slight  movement  in  this 
direction  completes  a  connection  to  the  magnetic  switch,  which 
thereupon  closes  the  motor  circuit  through  all  of  the  resistance, 
starting  the  pump  motor. 

Inasmuch  as  the  pilot  continues  to  move  the  cross-head 
toward  the  right,  the  speed  of  the  pump  will  be  gradually 
increased  until,  at  a  point  about  midway  of  its  travel,  all  of 
the  resistance  in  the  armature  circuit  of  the  motor  will  have 
been  cut  out  upon  the  upper  segments  and  further  movement 
then  serves  to  weaken  the  field.  This  is  accomplishd  by  means 
of  the  contact  buttons  shown  just  below  the  screw  shaft. 

As  soon  as  the  cross-head  has  weakened  the  field  to  its  mini- 
mum value  and  thus  speeded  the  motor  up  to  its  maximum 
point,  a  limit  switch  stops  the  pilot  motor  and  thus  prevents 
further  motion  in  that  direction.  As  soon  as  the  pump  working 
this  at  its  maximum  speed  has  produced  a  vacuum  in  the 
cleaning  system  of,  say,  12  in.  of  mercury,  the  cross-head  will 
begin  to  move  backward  and  reduce  the  speed  to  a  point  cor- 
responding with  the  air  required. 

T^his  control  of  the  pilot  motor  is  accomplished  by  means  of 
what  is  termed  "inspirator  type  vacuum  contactor."  This 
apparatus  is  shown  more  in  detail  in  Fig.  103,  and  consists  of 
a  diaphgram  closing  one  side  of  a  chamber.  The  diaphragm 
is  pressed  outward  by  an  internal  spring  whose  tension  may 
be  adjusted  by  means  of  a  hexagonal  head  cap  screw,  visible 
in  the  photograph  of  the  complete  regulator. 

The  diaphragm  is  coupled  to  a  pivoted  arm  carrying  insu- 
lated conical-pointed  silver  screws,  so  located  that  they  enter 
holes  in  small  silver  plates  mounted  on  opposite  sides,  respec- 


CONTROL  173 

tively,  of  the  upper  and  lower  contact  posts.  These  contact 
posts  are  hollow  and  communicate  with  the  diaphragm  chamber, 
which  latter  is  connected  by  piping  to  the  vacuum  system. 

Normally,  the  internal  spring  forces  the  diaphragm  over  so 
that  the  lever  makes  contact  with  the  lower  post.  This  serves 
to  drive  the  pilot  motor  in  a  direction  •  to  move  the  cross-head 
to  increase  the  speed  of  the  pump.  When  the  degree  of  vacuum 
for  which  the  apparatus  is  adjusted  is  reached  the  lever  starts 
to  move  toward  the  left  hand,  and  in  so  doing  stops  the  pilot 
motor.  This  maintains  the  pump  speed  at  that  particular  value. 
Should  the  vacuum  increase  to  a  sufficient  degree  the  lever 
will  be  drawn  further  over  toward  the  left  and  contact  will 
then  be  established  with  the  upper  post,  which  will  cause  the 
pilot  motor  to  move  the  cross-head  to  the  left,  and  thus  decrease 
the  pump  motor  speed. 

Inasmuch  as  the  motion  of  the  diaphragm  lever  is  very  grad- 
ual, destructive  arcing  would  take  place  at  the  pilot  motor  con- 
tacts were  it  not  for  the  small  openings  in  the  silver  contact 
plates,  which,  as  the  pointed  screw  leaves  the  hole,  immediately 
sucks  the  arc  inward  and  extinguishes  it. 

This  method  of  preventing  arcing  is  exceedingly  unique  and 
is  subject  to  patents  now  pending. 

It  is  possible  to  adjust  the  high  and  low  limits  by  changing 
the  setting  of  the  pointed  silver  screws,  the  usual  adjustments 
being  such  as  to  maintain  the  vacuum  within  2  in.  of  mercury. 
The  speed  of  the  pilot  motor  may  be  adjusted  by  means  of 
the  small  link  shown  in  the  upper  left-hand  corner  of  the  panels 
to  correspond  with  the  capacity  of  the  system,  it  being  found 
that  systems  of  large  capacity  require  a  slower  motion  than 
those  in  which  the  amount  of  piping,  etc.,  is  less  for  the  same 
size  of  pump.  In  practice,  the  regulator  will  very  quickly  find 
the  position  corresponding  to  the  proper  speed  for  the  number 
of  outlets  in  use,  and  only  moves  a  slight  amount  either  side 
of  this  particular  position. 

With  this  regulator  it  is  possible  to  employ  remote  control 
permitting  the  establishment  of  vacuum  in  the  piping  system 
by  the  turning  of  a  pilot  switch  located  at  any  point  in  the 
building.  If  desired,  several  such  switches  may  be  placed  in 


174  VACUUM    CLEANING    SYSTEMS 

parallel,  and,  under  these  conditions,  the  turning  on  of  any 
switch  will  establish  the  vacuum  supply  which  will  be  main- 
tained until  all  of  the  pilot  switches  are  turned  off.  By  this 
means  it  is  possible  to  have  several  janitors  working  at  the 
same  time  on  different  floors  of  the  building,  and  each  will  be 
independent  of  the  others  in  his  control  of  the  vacuum;  al- 
though one  man  may  finish  and  turn  off  the  switch  on  his  floor, 
the  pump  will  not  be  stopped  if  the  vacuum  is  still  required  by 
workers  on  other  floors. 

When  the  total  size  of  one  installation  becomes  greater  than 
25  H.  P.,  it  is  found  desirable  to  provide  two  pumping  units, 
and,  in  this  case,  the  same  system  is  applicable.  The  cross- 
head  is  then  arranged  to  start  first  one  pump  and  increase  its 
speed  to  a  maximum.  If  this  does  not  supply  Idie  necessary 
amount  of  air,  the  cross-head  continues  to  move,  and  starts  the 
second  pump,  which,  will  then  be  run  at  a  necessary  speed  to 
supply  the  remaining  amount  of  air. 

The  first  pump  always  remains  in  motion  at  its  point  of 
highest  efficiency.  It  is  evident  that  this  duplex  arrangement 
is  more  efficient  than  one  large  pump  when  only  a  very  few 
sweepers  are  in  operation,  since,  for  this  condition,  the  very 
large  pump  would  have  to  be  run  at  such  a  slow  speed  that  the 
armature  resistance  would  be  in  circuit,  while  the  single  smaller 
pump  would  be  running  at  a  more  efficient  speed  and  with  less 
proportionate  motor  losses. 

In  duplex  outfits  switches  are  provided  for  disconnecting 
either  motor  in  case  of  its  being  necessary  to  clean  or  repair 
either  unit.  When  so  disconnected  the  other  unit  may  be  oper- 
ated and  maintain  the  same  degree  of  vacuum  within  the  limits 
of  its  capacity. 

While  this  type  of  control  is  more  economical  in  current  con- 
sumption than  either  of  the  former  types  described,  its  cost  is 
much  higher,  and  it  is  seldom  used  unless  specifically  ordered. 

When  the  centrifugal  type  of  vacuum  producers  is  used  no 
control  is  necessary,  as  the  inherent  feature  of  this  type  of 
apparatus  insures  a  practically  constant  vacuum  at  all  air  quan- 
tities within  the  capacity  of  the  machine. 


CHAPTER  XL 

SCRUBBING  SYSTEMS. 

Vacuum  cleaning  systems  in  which  appliances  for  scrubbing 
are  provided  in  addition  to  the  usual  appliances  for  the  removal 
of  the  dust  and  other  materials  in  a  dry  state  have  been  intro- 
duced by  a  few  manufacturers,  none  of  which  has  come  into 
general  use. 

The  usual  method  employed  is  to  provide  an  ordinary  corn 
scrubbing  brush  which  has  a  connection  to  the  water  supply  of 
the  building,  with  control  valves  in  the  tool  handle  for  regu- 
lating the  flow  of  water  to  the  brush.  Soap  is  applied  either  in 
the  form  of  soap  powder  sprinkled  on  the  floor,  in  a  liquid 
state  fed  into  the  water  supply  by  means  of  a  sight-feed  oil  cup 
or  soft  soap  in  a  plastic  state  fed  into  the  water  supply  by  means 
of  a  compression  grease  cup. 

In  any  case,  the  water  is  run  onto  the  floor  mixed  with  the 
soap  and  the  floor  scrubbed  by  manipulating  the  corn  brush, 
in  the  same  manner  that  an  ordinary  corn  scrubbing  brush 
without  attachments  would  be  used. 

After  the  dirt  has  been  loosened  from  the  floor,  the  floor  may 
be  rinsed  by  the  application  of  more  water.  The  water  is  then 
drawn  up  from  the  floor  by  the  suction  of  the  cleaning  machine, 
and  passes  through  the  hose  and  piping  system  to  the  separator 
and  vacuum  producer.  To  effectively  remove  the  water  a  rub- 
ber-faced tool  is  usually  employed.  In  one  system  this  rubber 
face  is  arranged  to  permit  the  corn  brush  to  be  fitted  over  same 
when  scrubbing  is  being  done,  and  the  brush  must  be  removed 
from  the  tool  before  the  water  can  be  drawn  up  from  the  floor. 
Other  manufacturers  provide  a  double-faced  tool  having  the 
brush  on  the  opposite  side  of  the  tool  from  the  rubber-faced 
slot.  By  reversing  the  tool,  scrubbing  and  mopping  can  be 
accomplished  without  the  removal  of  the  corn  brush  from  the 
tool,  which  is  more  convenient  for  the  operator. 

175 


176  VACUUM    CLEANING    SYSTEMS 

With  either  of  the  above  forms  of  scrubbing  tools  it  is  neces- 
sary or  desirable  to  cut  off  the  suction  to  the  mopping  attach- 
ment when  using  the  corn  brush,  and  it  is  also  necessary  to 
cut  off  the  water  supply  to  the  brush  when  using  the  mopping 
attachment.  One  system,  introduced  several  years  ago,  con- 
ducted the  water  to  the  brush  and  away  from  the  rubber-faced 
mopping  appliance  through  the  same  hose.  This  arrangement 
requires  the  use  of  a  special  'three-way  hose  cock,  which  had  to 
be  manipulated  frequently  during  the  scrubbing  operation, 
requiring  the  time  of  another  person  in  addition  to  the  operator, 
or  else  greatly  delaying  the  scrubbing  process  by  requiring  the 
operator  to  constantly  pass  back  and  forth  between  the  hose 
cock  and  the  scrubbing  tool.  This  method  of  supplying  water 
also  requires  the  use  of  a  removable  corn  brush  attached  over 
the  rubber  mopping  device. 

Other  forms  of  scrubbing  appliances  are  provided  with  sep- 
arate hose  for  the  water  supply  and  suction  and  with  valves 
in  the  handles  for  controlling  the  suction  and  water  supply. 
These  valves  to  be  efficient  and  quick  in  action  are  generally 
made  self-closing,  otherwise  they  will  be  short-lived,  as 
explained  in  Chapter  V.  When  springs  are  used  to  close  the 
valves,  the  hand  and  wrist  will  be  quickly  fatigued,  as  stated 
in  Chapter  V. 

With  either  of  the  above  systems  all  of  the  scrubbing,  that 
is,  the  agitation  of  the  brush,  has  to  be  performed  by  the  oper- 
ator, as  in  the  case  of  the  ordinary  scrubbing  brush.  However, 
the  combination  tool  is  much  heavier  and  clumsier  than  the 
ordinary  scrubbing  brush,  and  the  only  advantage  obtained  by 
using  this  heavy  and  clumsy  appliance  is  the  ability  to  supply 
water  without  carrying  it  in  buckets,  also  the  removal  of  the 
dirty  water  after  scrubbing.  These  appliances  cannot  be  termed 
mechanical  scrubbers,  nor  can  they  be  classed  with  scrubbing 
machines  with  motor-driven  brushes,  such  as  have  been  recently 
introduced. 

A  real  mechanical  scrubbing  device  for  use  with  a  vacuum 
cleaning  system  was  manufactured  by  Foster  &  Glidden,  of  Buf- 
falo, N.  Y.,  but  was  never  placed  on  the  market,  although  at 
least  one  is  in  commercial  operation  to-day.  This  machine  is 


SCRUBBING  SYSTEMS  177 

provided  with  a  turbine  motor  operated  by  the  air  current 
passing  through  the  machine.  This  turbine  revolves  a  pair  of 
scrubbing  brushes  turning  in  opposite  directions.  Water  is  fed 
through  a  separate  hose,  and  an  auxiliary  air  inlet  is  opened 
when  the  suction  -under  the  brushes  is  closed,  in  order  to  supply 
the  necessary  air  to  keep  the  turbine  running.  Mr.  Foster 
states  that  he  has  experienced  no  trouble  in  operating  this 
machine  on  from  8  in.  to  12  in.  of  vacuum,  being  able  to  scrub 
and  remove  the  dirt  and  water  with  one  operation.  The  speed 
with  which  the  work  was  done  depended  on  the  condition  of  the 
floor,  the  usual  rate,  as  given  by  Mr.  Foster,  being  from  10  to 
12  yds.  per  minute. 

Mr.  Foster  also  states  that  he  has  not  pushed  the  introduction 
of  this  scrubber,  as  he  considers  it  so  far  ahead  of  the  times  as 
to  require  the  education  of  the  public  in  the  use  of  the  hose 
and  ordinary  vacuum  cleaning  tools  before  users  would  be 
capable  of  successfully  operating  this  type  of  scrubber. 

The  author  considers  this  condition  to  be  lamentable  if  true, 
for  until  some  such  appliance  is  in  commercial  use  scrubbing 
attachments  to  a  vacuum  cleaning  system  can  never  compete 
with  the  mechanical  scrubbing  machines  now  on  the  market, 
and  are  little  if  any  better  than  the  old  method  of  scrub- 
brush,  mop  and  pail,  and  certainly  not  as  rapid  in  operation. 

When  the  vacuum  cleaning  systems  combine  scrubbing  with 
dry  cleaning,  the  separator  and  vacuum  producer  must  pro- 
vide for  the  removal  of  water  as  well  as  air.  A  few  manufac- 
turers have  attempted  this,  among  which  are  the  makers  of  the 
Rotrex  system,  described  in  Chapter  IX,  in  which  the  water 
is  passed  through  the  pump  and  into  the  sewer  under  sufficient 
pressure  to  overcome  the  friction  in  the  exhaust  pipe  through 
which  the  expelled  air  passes  after  leaving  the  separator.  This 
may  be  sufficient  to  force  the  trap  seals  of  the  plumbing  system, 
and,  if  used,  the  discharge  connection  should  be  made  to  the 
sewer  outside  the  main  running  trap,  close  to  the  fresh  air 
inlet.  As  large  articles  cannot  be  allowed  to  pass  through  the 
pump,  a  screen  is  necessary  on  the  inlet  side  of  the  vacuum 
producer,  but  this  may  give  trouble,  due  to  the  clogging  with 
litter. 


178  VACUUM    CLEANING    SYSTEMS 

The  Atwood  Vacuum  Cleaner  Company  uses  a  wet  tank  on 
the  suction  side  of  the  vacuum  producer  into  which  the  dirt 
and  water  are  discharged,  the  air  being  separated  and  passed  to 
the  vacuum  producer.  When  this  tank  becomes  partly  filled 
it  is  necessary  to  shut  down  the  plant  and  empty  the  contents 
of  the  tank  by  gravity  into  the  sewer. 

This  method  overcomes  the  objections  to  clogged  screens  and 
forced  trap  seals,  and  all  litter  is  discharged  direct  to  the  sewer, 
together  with  a  quantity  of  water  which  is  presumably  sufficient 
to  flush  the  litter  through  the  sewer.  The  last  named  system  is 
still  open  to  two  objections;  first,  it  is  not  automatic,  and,  if 
neglected,  the  tank  will  fill  with  water  and  force  same  into  the 
vacuum  producer.  With  the  Root  type  of  vacuum  pump  this 
will  do  little  harm  unless  a  large  quantity  of  floating  litter 
should  pass  into  the  pump.  Second,  the  system  may  be  oper- 
ated with  dry  renovators  exclusively  for  a  considerable  portion 
of  the  time,  in  which  case  the  contents  of  the  separator  may 
become  of  such  a  consistency  as  will  not  readily  flush  through 
the  sewer,  and  stoppage  of  the  same  may  occur. 

Another  separator  of  this  type  has  recently  been  patented  by 
E.  B.  Dunn,  the  originator  of  the  Dunn  Locke,  in  which  the 
mud  and  the  water  are  automatically  discharged  alternately 
from  one  of  two  separators,  'as  described  in  Chapter  VIII. 

Such  a  separator,  in  which  sufficient  water  is  automatically 
introduced  to  dilute  the  dirt  and  which  will  automatically 
empty  when  sufficiently  filled,  when  so  constructed  that  it  will 
operate  continuously,  is  considered  to  be  the  ideal  separator  for 
use  with  a  combined  cleaning  and  scrubbing  system.  Until  the 
mechanical  scrubber  and  an  automatically  operated  separator 
are  commercially  introduced  the  author  does  not  consider  that 
the  use  of  scrubbing  attachments,  in  connection  with  the  vacuum 
cleaning  system,  is  advisable. 


CHAPTER  XII. 

SELECTION  OF  CLEANING  PLANT. 

We  have  considered  in  detail  the  various  appliances  which, 
taken  together,  make  a  complete  vacuum  cleaning  system,  but 
without  considering  their  relation  to  one  another.  It  now  be- 
comes necessary  to  choose  an  exact  type  and  form  of  each  of 
these  appliances  which  will  produce  in  combination  a  com- 
plete vacuum  cleaning  system  best  suited  to  the  conditions  to 
be  met  in  a  given  installation. 

In  selecting  a  vacuum  cleaning  system  consideration  must  be 
given  to  the  character  of  the  material  to  be  removed,  the  kind 
and  quality  of  the  surfaces  to  be  cleaned,  the  rate  at  which 
cleaning  must  be  done,  the  extent  of  the  cleaning  system,  and 
the  cost  of  labor  to  operate  the  system,  all  of  which  must  be 
considered  in  each  step  in  the  selection  of  a  suitable  plant. 

In  assembling  the  complete  system,  the  author  will  take  up 
the  various  parts  thereof  in  the  order  in  which  they  were  dis- 
cussed in  the  preceding  chapters. 

Renovators. —  The  selection  of  renovators  is  the  most  impor- 
tant step  in  making  up  a  vacuum  cleaning  system,  as  the  entire 
makeup  of  the  system,  whether  good  or  bad,  is  dependent  on 
the  proper  selection  of  these  tools.  The  carpet  renovator  is 
generally  considered  first  in  importance,  because  the  cleaning 
of  carpets  has  nearly  always  been  found  to  be  the  principal  field 
of  usefulness  in  vacuum  cleaning  work.  This  is  due,  perhaps, 
largely  to  the  fact  that  from  the  beginning  of  the  art  of  vacuum 
cleaning,  this  function  of  the  system  has  been  held  before  the 
eyes  of  the  public  by  the  manufacturers  of  the  earlier  systems. 
Nearly  all  demonstrations  of  cleaning  systems  shown  to  the 
public  consist  of  the  removal  of  ordinary  wheat  flour  from  a 
carpet.  The  reason  for  this  is  two-fold;  first,  because  it  is 
the  most  striking  demonstration  to  the  eye  of  the  layman,  and, 
second,  it  is  the  easiest  to  accomplish  with  a  small  air  displace- 

179 


180  VACUUM    CLEANING    SYSTEMS 

ment  and  small  power,  which  was  characteristic  of  the  apparatus 
made  by  these  manufacturers. 

The  author  was  at  one  time  of  the  opinion  that  this  function 
of  the.  cleaning  plant  was  given  too  much  prominence  by 
builders  of  systems  having  small  air  displacement,  and  letters 
were  sent  to  the  officials  in  charge  of  sixteen  Government 
buildings  in  which  vacuum  cleaning  systems  were  installed, 
asking  them,  among  other  questions,  whether  the  cleaning  sys- 
tem was  used  to  any  extent  in  cleaning  bare  floors,  of  which 
there  were  large  areas,  both  wood  and  marble,  in  the  buildings 
in  question.  The  plants  installed  were  of  various  makes,  some 
of  which  maintained  12  in.  mercury  at  the  separator  and  used 
1-in.  hose,  while  about  an  equal  number  of  others  maintained 
6  in.  mercury  at  the  separator  and  used  1^2 -in.  hose.  The 
answers  showed  that  out  of  the  sixteen  buildings  the  cleaner 
was  used  on  bare  floors  in  but  two  of  the  buildings.  One 
writer,  who  had  a  plant  maintaining  6-in.  vacuum,  provided 
with  Type  F  renovators  and  1^2 -in.  hose,  stated  that  he  had 
tried  cleaning  bare  floors  without  success,  as  the  renovator  and 
hose  became  so  clogged  with  litter  as  to  be  inoperative.  The 
majority  stated  that  the  cleaning  system  displaced  brooms  on 
carpets  and  rugs  and  several  stated  that  the  cleaning  system 
was  used  to  advantage  in  cleaning  walls,  cases,  pigeon  holes 
and  relief  work. 

This  indicates  that  for  the  average  office  and  departmental 
building  the  cleaning  of  carpets  is  the  most  important  function 
of  the  vacuum  cleaner.  This  is  also  true  of  residence  work. 
Schools,  department  stores  and  manufacturing  buildings  con- 
tain very  little  floor  space  covered  with  carpets,  and  in  buildings 
of  this  chcaracter  the  cleaning  of  bare  floors  is  of  the  greatest 
importance.  In  such  cases  the  efficiency  of  the  carpet  renovator 
can  be  sacrificed  to  a  more  efficient  and  economical  operation  of 
bare  floor  renovators. 

In  a  building  where  carpet  cleaning  is  an  important  function 
of  the  cleaning  system,  the  selection  of  the  carpet  renovator  is 
most  important.  Of  all  the  various  types  of  carpet  renovators 
discussed  in  Chapter  III,  only  two  need  to  be  considered,  Type 
A  and  Type  F.  Of  these,  Type  A  is  superior  in  all  respects 


•    f 

SELECTION  OF  CLEANING  PLANT  181 

except  the  picking  up  of  large  litter,  'and,  unless  the  character 
of  the  material  to  be  removed  contains  a  large  amount  of  mate- 
rial which  can  be  picked  up  by  Type  F  renovator  that  will  not 
pass  Type  A,  Type  A  renovator  should  always  be  used.  Even 
when  Type  F  renovators  are  desirable,  the  writer  considers  that 
the  plant  should  still  contain  some  Type  A  renovators  for  use 
in  places  where  this  unusual  litter  will  not  be  encountered. 

Among  the  bare  floor  renovators,  described  in  Chapter  IV, 
only  the  one  having  a  felt  face,  curved  to  permit  its  running 
over  the  dirt,  is  worthy  of  serious  consideration.  This  renovator 
requires  an  inlet  or  vacuum  breaker  to  keep  same  from  sticking 
to  the  surface  cleaned,  the  extent  of  such  opening  being 
dependent  on  the  vacuum  maintained  in  the  carpet  renovators, 
as  explained  in  Chapter  VII. 

When  carpet  cleaning  is  considered  as  of  secondary  impor- 
tance to  bare  floor  cleaning,  the  degree  of  vacuum  maintained 
at  the  separators  may  be  reduced  to  that  which  will  produce  a 
vacuum  of  1  in.  mercury  at  the  bare  floor  renovator,  allowing 
the  vacuum  maintained  at  the  carpet  renovator  to  be  what- 
ever the  conditions  of  hose  and  pipe  line  will  produce.  Under 
such  conditions,  the  area  of  the  inrush  or  vacuum  breaker  in 
the  bare  floor  renovator  may  be  reduced  considerably. 

The  use  of  brush  renovators  is  dependent  on  the  capacity  of 
the  air  exhauster  supplied,  as  explained  in  Chapter  VI.  If  it 
is  decided  that  brush  renovators  are  necessary,  then  the  "large 
volume"  exhauster  must  be  installed.  The  advisability  of  such 
installation  is  dependent  on  the  time  allowed  for  cleaning  and 
the  cost  of  the  operators.  In  residences  and  small  buildings 
where  the  cleaning  operations  can  be  done  with  one  or  even 
two  domestics  or  laborers,  very  little,  if  any,  saving  in  the  wages 
of  operators  can  be  effected  by  increasing  the  rate  at  which  the 
cleaning  can  be  done.  In  such  buildings  a  small-volume  plajit 
will  be  the  most  economical  in  first  cost  and  operation.  If  such 
a  plant  is  installed,  the  brush  renovators  should  be  omitted. 

In  cases  where  bare  floor  cleaning  is  the  principal  function 
of  the  cleaning  system  the  extra  quantity  of  air  at  the  low 
vacuum  necessary  will  not  require  much  larger  expenditure  of 
power  than  that  needed  by  the  small'-volume  plants  when 


182  VACUUM    CLEANING    SYSTEMS 

maintaining  sufficient  vacuum  for  effective  carpet  cleaning  and 
brush  renovators  should  be  provided  with  systems  of  this  char- 
acter. 

Hose. — In  Chapter  VI  it  is  shown  that  when  carpet  reno- 
vators are  operated  efficiently  in  combination  with  bare  floor 
renovators,  1^4 -in.  hose  will  produce  the  best  results  with  the 
lowest  expenditure  of  power  at  the  hose  cock.  In  Chapter  VII 
it  is  shown  that  with  pipe  lines  of  ordinary  length  1*4 -in.  hose 
also  gives  the  best  results,  with  the  least  expenditure  of  power 
at  the  separator,  but  that  in  cases  of  exceedingly  long  pipe 
lines,  1-in.  hose  will  be  the  most  economical.  In  a  system  where 
bare  floor  cleaning  is  the  principal  function,  the  vacuum  to 
be  maintaineed  at  the  carpet  renovator  is  no  longer  considered, 
and  for  such  systems  the  largest  hose  which  can  easily  be  han- 
dled will  #ause  the  least  hose  friction  and  require  the  lowest 
vacuum  at  the  hose  cock.  It  is,  therefore,  the  most  economical 
to  use  on  such  a  system.  The  author  does  not  recommend  the 
use  of  a  hose  larger  than  1^-in.  diameter  for  this  type  of 
plant. 

The  proper  hose  sizes,  therefore,  will  be:  For  ordinary 
buildings  where  carpet  cleaning  is  important,  1*4 -in.  diameter. 
For  installations  with  unusually  long  lines  of  piping,  where 
carpet  cleaning  is  important,  1-in.  diameter. 

For  all  systems  where  carpet  cleaning  is  of  secondary  impor- 
tance, lj/2-in.  or  13^-in.  diameter. 

Pipe  Lines. —  Pipe  lines  should  always  be  as  large  as  pos- 
sible without  reducing  the  velocity  in  same  below  40  ft.  per 
second,  as  explained  in  Chapter  VII. 

Separators. —  The  type  of  separator  to  be  used  is  dependent 
on  the  type  of  vacuum  producer  adopted.  Where  reciprocating 
exhausters  are  used,  or  other  type  of  exhauster  where  there  is 
rubbing  contact  between  the  moving  parts  and  the  dust,  the 
combination  of  a  wet  and  dry  separator  is  recommended.  When 
rotary  or  centrifugal  exhausters  having  close  clearances  are 
used,  total  separators  with  bags  are  recommended.  When  ex- 
hausters with  large  clearances  are  operated,  partial  separators 
are  satisfactory. 

The  use  of  any  form  of  apparatus  contemplating  the  adoption 


SELECTION  OF  CLEANING  PLANT  183 

of  a  satisfactory  scrubbing  system  is  not  considered  advisable, 
as  the  author  believes  that  separators  for  handling  water  will  be 
improved  before  scrubbing  becomes  commercially  successful. 
Changes  in  the  existing  separators  can  be  made  when  satisfac- 
tory scrubbing  appliances  are  placed  on  the  market,  at  no 
greater  expense  than  would  be  necessary  to  bring  up  to  date 
any  of  the  present  systems  for  handling  water. 

Vacuum  Producers. —  The  selection  of  the  vacuum  producer 
is  dependent  on  the  degree  of  vacuum  that  must  be  maintained 
to  effectively  operate  the  system  selected.  For  the  operation  of 
a  system  where  carpet  cleaning  is  the  principal  function  and 
1^4 -in:,  hose  is  used,  the  vacuum  required  at  the  producer  will 
be  from  6  in.  to  9  in.  mercury.  Inspection  of  the  efficiency 
curves  of  the  various  types  of  vacuum  producers,  given  in 
Chapter  IX,  shows  that  the  two-impeller  rotary  pump  has  the 
highest  efficiency  at  this  vacuum. 

For  the  operation  of  systems  where  carpet  cleaning  is  the 
most  important  function  and  1-in.  hose  is  found  to  be  the  most 
economical,  14  in.  to  15  in.  of  vacuum  at  the  vacuum  producer 
is  necessary,  and  efficiency  curves,  given  in  Chapter  IX,  show 
that  the  piston  pump  is  the  best  suited  for  such  service. 

For  the  operation  of  'a  system  where  carpet  cleaning  is  of 
secondary  importance  a  vacuum  at  the  producer  of  from  2  in. 
to  4  in.  of  mercury  will  be  sufficient.  For  this  work,  the  multi- 
stage or  even  single-stage  centrifugal  fan  is  practically  as  effi- 
cient as  the  two-impeller  rotary,  and  will  be  lower  in  first  cost 
and  cost  of  maintenance.  Either  of  the  above  mentioned  vacuum 
producers  are  satisfactory  for  operating  a  system  of  this  type. 

Control. —  Every  system  of  more  than  one-sweeper  capacity 
in  which  a  displacement  type  of  exhauster  is  used  should  be 
provided  with  some  means  of  economically  controlling  the 
vacuum  at  the  producer.  On  one-sweeper  plants  an  automatic 
starter  which  will  stop  the  motor  when  the  vacuum  reaches  a 
point  2  in.  above  that  required  and  start  same  when  the  vacuum 
drops  to  1  in.  below  that  required  is  convenient,  but  not 
necessary. 

For  piston  pumps  and  all  other  displacement  pumps  fitted 
with  eduction  valves,  an  unloading  device,  which  closes  the 


184  VACUUM    CLEANING    SYSTEMS 

suction  when  the  necessary  vacuum  is  exceeded,  is  the  least 
expensive  to  install  and  gives  very  good  economy  when  the 
demand  on  the  plant  is  fairly  continuous  during  the  time  it  is 
in  operation.  Where  the  service  is  intermittent  and  required 
at  nearly  all  hours,  the  Cutler  Hammer  control,  described  in 
Chapter  X,  is  the  most  economical. 

With  displacement  exhausters  having  no  eduction  valves, 
the  by-pass  type  of  control  is  satisfactory  where  the  service 
is  continuous,  but  is  not  as  economical,  as  the  unloader  used 
with  producers  having  eduction  valves  and  the  Cutler  Hammer 
control  is  more  efficient  under  all  conditions  of  service.  Cen- 
trifugal exhausters  need  no  control,  as  vacuum  control  is  an 
inherent  feature  of  these  machines. 

Summing  up  the  subject,  we  can  divide  the  vacuum  cleaning 
systems  into  four  classes,  each  of  which  requires  a  different 
selection  of  appliances.  They  are  as  follows: 

Class  i. —  Plant  for  residence  or  small  office  or  departmental 
building,  to  be  not  more  than  one-sweeper  capacity. 

Renovators:  See  list  given  for  "small  volume"  plant.  Chap- 
ter IV. 

Hose:     I^-in.  diameter. 

Separator:    Centrifugal,  dry,  with  bag  or  screen. 

Vacuum  Producer:  Two  impeller,  rotary,  alternate  centrifu- 
gal fan.  Capacity,  30  cu  ft.  of  free  air  per  minute,  4  in. 
vacuum  at  producer. 

Control:     Automatic  starter,  operated  by  vacuum. 

Size  of  motor :    y2  to  1  H.  P. 

Class  2. —  Large  office  or  departmental  building  where  car- 
pet cleaning  is  important  and  pipe  lines  are  of  reasonable 
length. 

Renovators:  See  list  given  for  "large  volume"  plant,  Chap- 
ter IV. 

Hose:     1^-in.  diameter. 

Separator:     Centrifugal,  dry,  with  bag  or  screen. 

Vacuum  Producer:  Two  impeller,  rotary.  Capacity,  70  cu. 
ft.  of  free  air  per  minute  for  each  sweeper  of  plant  capacity  at 
7  in.  to  9  in.  vacuum. 

Size  of  motor:     2l/2  H.  P.  per  sweeper  capacity. 


SELECTION  OF  CLEANING  PLANT  185 

Control :      Cutler   Hammer. 

Class  3. — Large  building  or  group  of  buildings  whert  carpK 
cleaning  is  important  and  long  lines  of  piping  are  necessary. 

Renovator:    See  list  for  " large  volume"  plants,  Chapter  IV. 

Hose :      1-in.   diameter. 

Separators:     One  centrifugal  dry  and  one  wet. 

Vacuum  Producer:  Piston  type  pump.  Capacity,  45  cu.  ft. 
of  free  air  per  minute  for  each  sweeper  of  plant  capacity  at 
14  in.  vacuum. 

Size  of  motor:    4  H.  P.  for  each  sweeper  of  plant  capacity. 

Control :  Automatic  unloader  for  continuous  service.  Cutler 
Hammer  for  intermittent  work  at  all  times. 

Class  4. —  Large  or  small  plant  where  carpet  cleaning  is  not 
an  important  function  of  the  cleaning  system. 

Renovators:     Same  as  for  Class  3. 

Hose:    lJ/£  in.  or  1^4  in. 

Separators :  One  centrifugal,  dry,  with  or  without  bag,  accord- 
ing to  type  of  exhauster  adopted. 

Vacuum  Producer:  Centrifugal  fan  or  two-impeller  rotary 
pump. 

Capacity:  70  to  90  cu.  ft.  of  free  air  per  minute  for  each 
sweeper  of  plant  capacity,  with  a  vacuum  of  from  2  in.  to  3  in. 
mercury. 

Size  of  motor:  1  to  2  H.  P.  for  each  sweeper  of  plant 
capacity. 

Control:  With  centrifugal  fan,  none;  with  pump,  Cutler 
Hammer. 

It  is  interesting  to  note  that  to  produce  the  most  efficient 
plant  for  all  of  the  four  cases  named,  all  of  the  various  types 
of  vacuum  cleaning  systems  which  have  come  into  general  use 
have  to  be  operated  each  under  its  most  favorable  conditions 
and  the  engineer  should  select  his  plant  to  best  fulfill  the  condi- 
tions of  the  special  case  at  hand,  just  as  he  would  select  his 
prime  mover  for  an  electric  generating  plant  according  to  its 
size  -and  location.  There  should  be  no  more  reason  why  any 
one  of  these  systems  should  attempt  to  fulfill  the  requirements 
of  every  installation  than  there  would  be  for  a  manufacturer 
of  steam  engines  to  attempt  to  use  the  same  type  of  engine  to 


186  VACUUM    CLEANING    SYSTEMS 

drive  a  generator  under  all  conditions.  The  writer  believes  that 
this  condition  will  soon  be  realized  by  all  manufacturers  of 
vacuum  cleaning  systems  and  that  they  will  endeavor  to  install 
apparatus  of  the  type  best  suited  to  the  conditions  to  be  met  in 
each  case. 


CHAPTER  XIII. 
TESTS. 

Having  decided  on  the  type  of  vacuum  cleaning  system  that 
is  best  suited  to  the  conditions  of  the  particular  building  in 
which  it  is  to  be  installed,  it  then  becomes  necessary  to  ascer- 
tain what  are  the  tests  necessary  to  determine  whether  the 
installation  will  produce  the  desired  results. 

If  the  installation  is  one  in  which  carpet  cleaning  is  impor- 
tant and  the  plant  is  of  more  than  one-sweeper  capacity,  the 
exhauster  must  be  of  sufficient  capacity  to  produce  a  vacuum  of 
not  less  than  4  in.  mercury  at  a  carpet  renovator  attached  to 
any  inlet  on  the  piping  system,  when  the  plant  is  operating 
other  renovators  of  any  type  attached  to  any  of  the  other  inlets 
corresponding  to  one  less  than  the  total  sweeper  capacity  of  the 
system. 

When  hose  lengths  as  short  as  25  ft.  can  be  used  on  any  or 
all  of  the  outlets,  it  has  been  demonstrated  in  Chapter  VII  that 
an  air  removal  of  70  cu.  ft.  of  free  air  per  minute  for  each 
sweeper  of  plant  capacity  is  necessary,  no  matter  what  size  of 
hose  is  used.  It  was  also  shown  that  where  pipe  lines  are  very 
long  and  it  is  possible  to  always  use  100  ft.  of  hose,  efficient 
cleaning  can  be  done  with  less  expenditure  of  power  with  an 
air  displacement  of  45  cu.  ft.  of  free  air  for  each  sweeper  of 
plant  capacity. 

Many  methods  have  been  recommended  for  testing  a  cleaning 
plant.  Perhaps  the  earliest  was  the  maintaining  of  15  in.  of 
vacuum  at  the  vacuum  producer  with  carpet  renovators  each 
attached  to  100  ft.  of  hose,  equal  in  number  to  the  sweeper 
capacity  of  the  plant  in  operation  on  carpets.  Another  test  is 
to  'attach  100-ft.  lengths  of  hose  to  inlets  on  the  system,  with 
the  ends  wide  open,  equal  in  number  to  the  sweeper  capacity 
of  the  plant,  and  require  the  pump  to  maintain  a  vacuum  of 
15  in.  mercury. 

187 


188  VACUUM    CLEANING    SYSTEMS 

Both  of  these  tests  were  recommended  for  use  on  plants 
where  1-in.  diameter  hose  was  provided  and  the  results  are 
dependent  largely  on  the  size  and  length  of  the  piping  system. 
With  an  average-sized  system,  the  first  test  will  require  an 
exhaustion  of  approximately  25  cu.  ft.  of  free  air  per  renovator 
per  minute  if  Type  A  renovators  are  used.  The  second  test 
will  require  an  exhaustion  of  approximately  50  cu.  ft.  of  free 
air  per  open  hose  per  minute.  Neither  of  these  tests  will 
insure  a  plant  of  sufficient  capacity  to  do  effective  cleaning 
where  25-ft.  lengths  of  1-in.  hose  can  be  used  or  if  larger  bore 
than  1-in.  hose  be  used. 

If  these  tests  are  required  with  bores  larger  than  1-in.  diame- 
ter and  the  vacuum  is  maintained  the  same  as  before,  air  ex- 
haustion with  1*4 -in.  open  hose  will  be  approximately  70  cu.  ft. 
of  free  air  per  open  hose,  and  with  lj/2-in.  hose,  approximately 
150  cu.  ft.  per  open  hose,  while,  if  carpet  renovators  be  used, 
the  vacuum  at  the  renovator  would  be  from  7  to  9  in.  of  mer- 
cury. In  either  case,  the  vacuum  required  to  be  maintained  at 
the  separators  is  higher  than  is  necessary  to  produce  economical 
cleaning  with  either  1^4-in.  or  1^2 -in.  hose. 

Tests  with  carpet  renovators  attached  to  100  ft.  hose  lines  in 
number  equal  to  the  capacity  of  the  plant,  and  a  vacuum  of 
±y2  in.  of  mercury  at  the  renovator  will  result  in  an  exhaustion 
below  that  necessary  to  produce  efficient  cleaning  when  bare  floor 
renovators  and  carpet  renovators  with  shorter  hose  lines  are 
used,  as  is  likely  to  occur  in  actual  practice. 

Again,  open  hose  tests  require  a  variable  length  of  hose  to 
be  used  in  order  to  obtain  the  same  air  quantity  with  the  proper 
vacuum  at  the  separator  for  economical  operation. 

If  70  cu.  ft.  of  air  is  desired,  as  in  the  case  of  Class  2  plant 
(Chapter  XII),  the  hose  lengths  should  be: 

50  ft.  1  in.  diameter.     12  in.  vacuum  at  separator. 

75  ft.  1J4   in-  diameter.     9  in.  vacuum  at  separator. 

125  ft.  \y2  in.  diameter.     6  in.  vacuum  at  separator. 

Any  of  these  lengths  would  give  satisfactory  cleaning  with 
one  carpet  renovator  in  use,  together  with  sufficient  bare  floor 


SELECTION  OF  CLEANING  PLANT  189 

renovators  to  equal  the  capacity  of  the  plant.  This  is  a  pos- 
sible condition  in  any  plant. 

Another  method  of  testing  is  to  measure  the  actual  air  passing 
through  a  given  length  of  hose  and  require  sufficient  vacuum 
at  the  separator  <to  produce  this  flow.  This  method  is  open  to 
the  objection  that  variation  in  the  size  of  the  hose  will  result  in 
considerable  variation  in  the  vacuum  at  the  separator  and  con- 
ditions of  hose  lengths  may  be  such  that  when  carpet  reno- 
vators are  attached  to  the  hose,  the  vacuum  at  the  renovator 
will  vary  according  to  the  resistance  offered  to  the  passage  of 
the  air  by  the  friction  in  the  hose.  With  the  small  hose,  the 
friction  will  be  greatest,  and  the  reduction  in  the  quantity  of 
air  passing  the  renovator  from  that  passing  an  open  hose  will 
result  in  the  greatest  reduction  in  friction  loss  through  the  hose 
and  produce  the  highest  vacuum  at  the  renovator.  This  will 
cause  a  widely  different  vacuum  at  the  renovator  with  different 
sizes  of  hose,  each  of  which  passes  the  same  amount  of  air  with 
the  end  of  hose  open. 

What  is  desired  in  cleaning  operations  is  a  certain  degree  of 
vacuum  at  the  carpet  renovator,  with  the  system  operated  under 
the  same  conditions  that  will  obtain  in  practical  cleaning,  and 
with  cleaaners  of  various  types  attached  to  hose  ends  equal  in 
number  to  the  capacity  of  the  plant. 

The  most  rational  system  of  testing  is  one  in  which  the  actual 
conditions  of  air  quantity  and  vacuum  are  measured  at  the  hose 
ends.  This  can  be  obtained  by  actually  attaching  cleaning 
tools  to  the  hose  ends  and  measuring  the  vacuum  within  the 
renovator.  However,  a  wide  variation  in  vacuum  will  result 
when  the  renovator  is  moved  along  the  carpet,  and  this  variation 
will  be  different  with  different  operators  and  different  grades 
of  carpet  to  such  an  extent  as  to  render  it  impossible  to  actually 
meet  any  reequirements  that  may  be  specified,  unless  a  con- 
siderable variation  in  vacuum  is  permitted. 

It  is  also  possible  for  an  operator  to  become  so.  expert  in  the 
manipulation  of  the  renovators  as  to  be  able  to  meet  the  speci- 
fication requirements  with  a  plant  which  will  not  give  satisfac- 
tory results  in  actual  operation. 


190 


VACUUM    CLEANING    SYSTEMS 


The  most  satisfactory  method  of  testing  that  has  been  devised 
is  the  use  of  an  orifice  of  proper  size  fixed  to  the  hose  end  and 
measure  the  vacuum  just  inside  of  this  orifice.  In  making 
such  measurements  care  must  be  taken  that  the  tube  connecting 
to  the  vacuum  gauge  is  not  inserted  in  such  a  manner  that  the 
air  velocity  affects  the  reading  of  the  vacuum  gauge.  The 
shape  of  orifice  must  also  be  carefully  specified,  as  the  round- 
ing of  the  edges  of  the  opening  will  greatly  increase  the  quan- 
tity of  air  passing  a  given-sized  orificee.  The  best  standard 
is  a  sharp-edged  orifice  in  a  tihin  disk  which  has  a  coefficient 
of  ingress  of  approximately  65%. 

A  convenient  form  of  testing  appliance  based  on  the  orifice 
test  is  the  vacometer,  manufactured  by  the  Spencer  Turbine 
Cleaner  Company  and  shown  in  Fig.  104. 
This  device  consists  of  a  spherical  aluminum 
casting,  with  a  1-in.  diameter  hole  on  the 
equatorial  circle,  a  vacuum  gauge  being  at- 
tached to  one  polar  extremity,  the  other  being 
attached  to  the  end  of  the  hose.  A  ring  hav- 
ing a  slip  fit  is  placed  around  the  equatorial 
circle  in  which  openings  varying  from  ^-in. 
to  %-in.  diameter  are  drilled.  By  turning 
this  ring  any  of  the  orifices  may  be  made  to 
register  with  the  opening  in  the  sphere.  The 
opening  to  which  the  vacuum  gauge  is  at- 
tached .is  so  located  that  it  is  not  affected  by 
the  entering  air  current,  and  its  readings 
are  not  affected  by  the  velocity  head. 

Experiments  with  this  instrument  in  con- 
nection with  a  Pi  tot  tube  show  that  a  3^ -in. 
diameter  orifice  is  equivalent  to  a  Type  A 
carpet  renovator,  a  5/8-in.  orifice  to  a  Type 
F  renovator  and  a  ^g-in.  orifice  to  a  bare  floor  renovator. 

With  instruments  of  this  type  equal  in  number  to  the  ca- 
pacity of  the  plant  in  sweepers,  attached  to  the  ends  of  the 
cleaning  hose,  it  is  possible  to  obtain  uniform  conditions  equal 
to  the  average  results  that  will  be  obtained  in  actual  practice 


FIG.  104.  VACO- 
METER  FOR  USE 
IN  TESTING 
VACUUM  CLEAN- 
ING SYSTEMS. 


SELECTION  OF  CLEANING  PLANT  191 

with  renovators  attached  to  the  hose,  without  the  possibility 
of  expert  manipulation  of  the  renovators  affecting  the  results. 

The  proper  orifice  to  be  used  in  each  vacometer  during  the 
test  will  vary  with  the  character  of  the  service  for  which  the 
plant  is  designed,  'and  the  author  recommends  the  following 
for  each  of  the  classes  of  plants  described  in  Chapter  XII: 

Class  1.  2-in.  mercury,  with  ^2 -in.  orifice,  maximum  length 
of  hose  to  be  used  in  actual  cleaning. 

Class  2.  One-half  the  inlets  ^-in-  orifice,  4.5  in.  mercury  at 
one  orifice  attached  at  end  of  longest  hose  desired  to  use  in 
practice,  the  remaining  J^-in.  outlets  on  shorter  hose  lengths. 
The  other  half  of  inlets  to  -have  J/g-in.  orifices  open  at  same 
time,  with  longest  hose  on  one-quarter  of  total  inlets  and  shortest 
on  the  balance. 

Class  3.  All  inlets  on  long  hose,  one^half  with  ^-in.  orifice, 
balance  with  %  in. 

Class  4.  All  inlets  to  'have  %-in.  orifice  and  1  in.  vacuum  at 
vacometer,  all  hose  lines  maximum  length. 


CHAPTER  XIV. 

SPECIFICATIONS. 

Before  the  engineer  begins  to  prepare  his  specifications  for 
a  proposed  vacuum  cleaning  system,  he  will  naturally  consider 
carefully  the  conditions  to  be  met  in  the  particular  installation 
contemplated.  Having  considered  these  conditions,  he  can 
readily  determine  the  type  of  system  that  will  operate  most 
efficiently  and  economically  under  such  conditions.  It  is,  there- 
fore, natural  to  assume  that  the  best  interests  of  his  clients 
can  be  obtained  by  confining  his  specifications  to  apparatus  of 
the  type  giving  the  most  efficient  results  for  the  special  condi- 
tions to  be  met.  However,  it  is  also  necessary  to  study  the  appar- 
atus on  the  market  to  determine  if  there  is  a  sufficient  number 
of  manufacturers  producing  the  particular  type  of  apparatus 
specified  to  insure  healthy  competition  and  reasonable  bids. 

It  becomes  necessary,  therefore,  to  examine  the  various 
systems  offered  by  the  manufacturers  in  order  to  determine  what 
competition  can  be  obtained. 

Apparatus  for  Class  1  or  Class  2,  if  confined  to  the  positive 
displacement  rotary  exhausters  of  the  two-impeller  type,  can 
be  obtained  from  at  least  seven  manufacturers.  If  the  centri- 
fugal fan  is  included,  at  least  three  other  manufacturers  can 
be  considered  and  in  either  case  a  healthy  competition  be  had. 

If  apparatus  of  Class  3  is  desired,  it  can  be  obtained  from 
at  least  three  manufacturers.  A  feiw  years  ago  more  manu- 
facturers of  systems  of  this  type  were  in  the  market.  Some 
of  these  have  dropped  out,  owing  to  the  comparatively  limited 
field  for  this  apparatus.  However,  there  are  still  enough  manu- 
facturers in  the  field  to  insure  competition. 

Apparatus  of  Class  4  has  been  especially  manufactured  by 
one  company.  However,  any  of  the  manufacturers  of  centri- 

192 


SPECIFICATIONS  193 

fugal  fan  type  of  apparatus  can  easily  meet  the  specification 
requirements  for  apparatus  of  the  character. 

It  is,  therefore,  evident  that  the  specification  of  apparatus  of 
the  type  best  suited  to  any  particular  installation  will  not 
result  in  lack  of  competition,  and  such  ia  procedure  would  appar- 
ently be  justified. 

There  are  installations,  such  as  those  for  public  buildings, 
where  it  may  be  advisable  from  an  administrative  standpoint 
to  allow  the  widest  competition  possible.  In  such  cases  the  engi- 
neer can  secure  the  best  results  for  his  clients  by  so  drawing  his 
specifications  as  to  include  all  types  of  apparatus,  fixing  care- 
fully the  test  requirements  to  be  met  and  requiring  each  bidder 
to  state  in  his  proposal  the  amount  of  power  required  to  operate 
his  apparatus  under  full  load,  three-quarter  load  and  half-load 
conditions,  and  to  base  the  award  of  the  contract  on  an  evalua- 
tion basis. 

To  determine  what  the  basis  of  this  evalution  shall  be  it  is 
first  necessary  to  ascertain  the  length  of  time  the  plant  will  be 
operated  at  each  of  the  loads  specified  and  find  the  annual 
cost  of  a  unit  of  power  to  operate  the  plant.  Assuming  the 
plant  has  a  life  of  ten  years,  we  can  charge  10%  depreciation, 
add  to  this  5%  for  interest  on  the  investment  and  1%  for  insur- 
ance. We  can  capitalize  the  saving  in  power  at  16%  and  use 
this  amount  as  a  basis  for  evaluation. 

As  an  example,  assume  one  bidder  guarantees  a  power  con- 
sumption of  1  K.  W.  less  at  full  load,  1.25  K.  W.  less  at  three- 
quarters  load  and  0.75  K.  W.  more  at  half  load  than  a  lower 
bidder.  Assume  the  plant  will  operate  500  hrs.  per  year  at  full 
load,  200  hrs.  at  three-quarters  load  and  300  hrs.  at  half  load. 
The  total  kilowatt  hours  saved  by  the  more  economical  plant 
will  be: 

Full   load   500X1= 500 

Three-quarter   load   200X1.25= 250 


Total  saving   750 

One-half  load,  300X0.75= 225 


Net  saving  (K.  W.  Hr.) 525 


194  VACUUM    CLEANING    SYSTEMS 

If  power  costs  5  cents  per  K.  W.  Hr.  the  yearly  saving  will 
be  $26.25,  which,  capitalized  at  16%,  will  equal  $164.00.  This 
is  the  amount  which  the  owner  would  be  justified  in  paying  for 
the  more  economical  plant  above  the  price  asked  for  the 
cheaper,  but  less  economical,  system. 

In  order  to  guard  against  any  bidder  guaranteeing  a  lower 
power  consumption  than  he  can  actually  show  on  test,  it  is 
necessary  to  impose  a  penalty  for  failure  to  meet  the  guarantee 
which  is  in  excess  of  the  increase  in  price  shown  to  be  justified 
by  the  evaluation. 

The  author  recommends  that  this  penalty  be  made  not  less 
than  150%  of  the  increase  in  price  shown  by  the  eyalution. 

Actually,  the  owner  will  not  lose  by  the  less  efficient  plant  any 
more  than  the  amount  shown  by  the  evaluation  if  'he  junks  the 
plant  at  the  end  of  ten  years.  However,  it  is  more  than  likely 
that  he  will  either  use  it  for  a  longer  time  or  will  be  able  to 
realize  something  for  the  plant  when  it  is  displaced.  The  in- 
creased penalty,  therefore,  is  justified,  and  it  is  absolutely 
necessary  to  make  this  penalty  greater  than  the  increased  value 
to  prevent  the  bidder  guaranteeing  a  power  consumption  lower 
than  he  can  show  on  test. 

The  following  pages  contain  sample  specifications  for  appar- 
atus of  each  of  the  four  classes  of  systems  described  in  Chap- 
ter XII  and  a  specification  permitting  the  widest  competition, 
with  evaluation  and  penalty  clauses! 

CLASS  i. 

PLANT  FOR   RESIDENCE   OR   SMALL   OFFICE   BUILDING   OF   ONE- 
SWEEPER  CAPACITY. 

1.  General  Description.  The  work  included  in  this  specifica- 
tion shall  be  the  installation  of  a  complete  vacuum  cleaning 
system  for  the  removal  of  dust  iand  dirt  from  rugs,  carpets, 
floors,  stairs,  furniture,  shelves,  walls  and  other  fixtures  and 
furnishings  throughout  the  building,  and  for  conveying  said 
dust  and  dirt  to  suitable  receptacles  located  where  shown, 
together  with  all  of  the  necessary  cleaning  tools,  hose,  piping. 


SPECIFICATIONS  195 

separators,  exhauster,  motor,  etc.,  as  hereafter  more  fully  speci- 
fied. 

2.  Exhauster.  The  exhauster  in  all  of  its  details  shall  be  made 
of  the  best  materials  suitable  for  the  purpose  and  shall  be  of 
approved  design  and  construction,   and  may  be  either  of  the 
positive  displacement   (rotary)   or  of  the  multi-stage  fan  type. 

3.  Rotary    Exhauster.  The    rotary     displacement    exhauster 
shall  be  either  of  the  two-impeller  type  or  of  type  having  single 
impeller  without  sliding  vanes  revolving  without  friction  con- 
tact with  case  and  with  oscillating  follower. 

4.  Exhausters  fitted  with  sliding  blade  or  blades  will  not  be 
acceptable. 

5.  All  parts  of  the  exhauster  shall  be  rigid  enough  to  retain 
their  shape  when  the  machine  is  working  under  maximum-load 
conditions. 

6.  The  impellers  must  be  machined  all  over  and  must  be  of 
such  shape  and  size  that  they  will  revolve  freely  and  not  touch 
each  other,  the  follower,  or  the  casing  (cylinder)  in  which  they 
are   placed,   but  the  clearance  must   be   of   the   least   possible 
amount  consistent  with  successful  operation. 

7.  The  shafts  must  be  of  steel  with  the  journals  ground  to 
size. 

8.  The  journal  boxes  must  be  long  and  rigidly  supported  by 
the  headplaites  and  placed  far  enough  from  the  headplates  to 
allow  the  placing  of  proper  stuffing  boxes  on  the  shafts. 

9.  The  shafts  of  two  impeller  exhausters  must  be  connected 
by  wide-faced  steel  gears,  cut  from  the  solid  and  securely  fast- 
ened to  the  shafts.    Follower  shaft  on  single  impeller  exhauster 
to  be  connected  to  impeller  shaft  by  crank  and  connecting  rod. 
The  gears  shall  run  in  suitable  oil-tight  gear  boxes  that  shall  be 
fitted  with  adequate  and  suitable  means  for  lubrication. 

10.  Centrifugal  Fan  Type.  The  centrifugal  fan  exhauster  to 
be  so  proportioned  and  constructed  as  to  handle  the  volume  of 
air  required  at  the  specified  vacuum  with  the  least  possible  loss. 
The  housing  shall  be  of  cast  iron  or  aluminum,  made  in  sections. 
The  housing  must  be  air-tight. 

11.  The  fan  wheels  to  be  constructed  of  steel  or  other  metal 
of  high  tensile  strength,  properly  reinforced,  and,  if  cast,  must 


196  VACUUM    CLEANING    SYSTEMS 

include  hub  and  arms  complete  in  one  piece.  If  the  fan  wheels 
are  built  up',  they  must  be  strongly  riveted  to  cast-iron,  steel  or 
brass  hubs  or  spiders. 

12.  The  fan  wheels  are  to  be  secured  to  shaft  with  a  feather 
and  set  screws,  or  with  left-hand  screw. 

13.  The  shaft  of  fan  exhauster  may  be  vertical  and  the  wheels 
so  mounted  that  their  weight  will  equalize  or  partly  equalize  the 
end  thrust,  or  the  end  thrust  may  be  balanced  by  the  magnetic 
pull  of  the  armature.     Shaft  may  be  horizontal  and  end  thrust 
taken  care  of  with  ball-bearing  thrust  rings. 

14.  The  journal  boxes  for  all  of  the  above  named  types  of 
exhausters  shall  be  of  the  design  best  adapted  for  the  purpose 
and  must  be  fitted  with  first-class  approved  continuous  lubri- 
cating devices,  either  sight  feed,  ring  oiler,  or  any  other  kind 
best  suited  for  the  work  or  design  of  apparatus  used. 

15.  Cooling.  The  rotary  type  of  exhauster  must  be  provided 
with  the  necessary  water  connections  to  properly  seal  and  cool 
the  pump.    Fan  type  of  exhauster  must  be  designed  to  operate 
continuously  without  a  rise  of  temperature  over  100°  F.  above 
room  temperature. 

16.  Speed.  Rotary  exhausters  shall  not  exceed  a  peripheral 
speed  of  1,100  ft.  per  minute  at  tips  of  impellers. 

17.  Centrifugal   fans  shall  not  exceed  peripheral  velocity  of 
22,000  ft.  per  minute  when  running  under  specified  full-load 
conditions. 

18.  Mounting.  The  exhauster,  motor  and  separators  shall  be 
mounted    as    a    unit    on    suitable    cast-iron    base    plate,    either 
mounted  on  legs  or  resting  on  the  basement  floor. 

19.  Drive.  The  exhauster  shall  be  driven  by  an  electric  motor, 
which  may  be  direct  connected  to  the  exhauster  shaft  or  be 
operated    with    an    oak-tanned   leather   belt,    or   by    cut   gear- 
ing.    Belt  and  gearing  are  to  be  of  ample  size  and  strength  for 
their  work  and  must  run  without  undue  noise  or  wear.     Means 
shall   be   provided    to   take   up    the    slack    of   the.  belt.     Fur- 
nish and  place  a  suitable  metal  guard  over  belt  and  pulley 
wheels  that  shall  prevent  oil  being  splashed  outside  of  the  base 
plate  and  prevent  clothing  being  caught. 

20.  If  the  exhauster  is  operated  through  cut  gearing,  the  gear- 


SPECIFICATIONS  197 

ing  must  be  inclosed  in  an  oil  and.  dust  proof  case,  which  shall 
be  fitted  with  means  for  copious  and  continuous  lubrication  of 
same. 

21.  Finish.  The  air  exhauster  and  motor  and  the  base  plate 
shall  be  finished  in  a  first-class  manner,  filled,  rubbed  down  and 
painted  at  least  one  coat  at  the  shop,  and  after  installation  shall 
receive  two  more  coats,  finishing  tint  to  be  as  directed. 

22.  Electric  Motor.  Motor  to  be  of  such  size  that  when  oper- 
ating under  test  conditions  it  will  not  be  under  less  than  three- 
fourths  nor  more  than  full-load  condition.     It  is  to  be  of  stand- 
ard make,  approved  by  the  architect. 

23.  Motor  to  be  wound  for  ....  volts  direct  current. 

24.  Armature  to  be  of  toothed-core  construction,  with  wind- 
ings thoroughly  insulated,  and  securely  fastened  in  place,  and 
must  be  balanced  both  mechanically  and  electrically. 

25.  Commutator  segments  must  be  of  drop-forged   or  hard- 
drawn  copper  of  highest  conductivity,  well  insulated  with  mica 
of  even  thickness  and  proper  hardness  to  insure  uniform  wear, 
and  shall   run  free  from  sparking  or  flashing  at  the  brushes 
under  all  conditions  of  speed.    It  must  be  free  from  all  def ects. 
and  have  'ample  bearing  surfaces  and  radial  depth  as  provision 
for  wear. 

26.  Brushes  to  be  of  carbon,  mounted  on  a  common  rocker 
arm  for  motor,  and  to  have  cross-sectional  area  of  not  less  than 
1  square  inch  for  each  35  amperes  of  current. 

27.  Brush  holders  to  be  of  a  design  to  prevent  chattering, 
with  individual  adjustment  in  tension  for  each  brush. 

28.  Bearings  to  be  of  an  approved  self-oiling  or  ring  type. 

29.  There  must   be   an   insulation  resistance   between  motor 
frame  and  field  coils,  armature  windings  and  brush  holders  of 
not  less  than  1  megohm. 

30.  Motor  must  be  capable  of  standing  a  breakdown  test  of 
1,500  volts  alternating  current.    Either  or  both  of  the  foregoing 
tests  to  be  applied  at  the  discretion  of  the  architect's  agent  at 
the  time  of  shop  tests. 

31.  The  maximum  rise  in  temperature  of  the  motor  at  a  con- 
tinuous run  (after  installation  at  building)   at  full  speed  and 
full-rated  load  for  a  period  of  eight  hours  must  not  exceed  50° 


198  VACUUM    CLEANING    SYSTEMS 

C.  in  windings  and  55°  C.  on  commutator  above  the  surrounding 
atmosphere. 

32.  Motor  to  be  finished  in  a  first-class  manner,  filled  and 
rubbed  down  and  painted  two  coats  at  the  shop,  and  after  in- 
stallation to  have  two  more  coats ;  finishing  tints  to  be  as  di- 
rected by  the  superintendent  of  the  building. 

33.  Tablet.  Furnish   and  mount   where   directed    a   polished 
slate  tablet  not  less  than  ^4  in-  thick,  having  mounted  thereon 
one  30jampere,  250-volt,  double-pole  knife  switch,  with  enclosed 
indicating  fuses,  and,  if  displacement  exhauster  is  furnished, 
one   automatic   self-starter   having   butt   contacts,    cutting   out 
starting  resistance  in  not  less  than  two  steps,  starter  to  be  con- 
trolled by  the  vacuum  in  separator,  and  shall  stop  motor  when 
vacuum  rises  2  in.  above  that  required  to  meet  test  requirements 
and  start  motor  when  vacuum  falls  to  that  required  for  working. 

34.  Electrical  Connections.  This  contractor  shall  run  feeders 
from  vacuum  cleaner  panel  in  switchboard  where  shown  to  the 
motor  panel  and  make  all  electrical  connections  between  panel 
and  motor,  etc. 

35.  All  wires  are  to  be  run  in  standard  steel  conduit,  except 
•those  that  are  so  short  as  to  be  self-supporting,  and  these  are 

to  be  cord  wrapped  or  otherwise  protected.     No  wire  smaller 
than  No.  8  to  be  used. 

36.  All  material  and  workmanship  to  be  strictly  first  class. 
Electrical  work  must  Show  an  insulation  resistance  of  at  least 
1  megohm,  and  to  be  in  strict  accordance  with  the  latest  edition 
of  the  "National  Electrical  Code." 

37.  Dust  Separator.  There  shall  be  one  dry  separator  located 
where  shown  on  plans,  having  a  volume  not  less  than  3  cu.  ft. 

38.  The  interior  arrangement  of  the  separator  shall  be  such 
that  no  part  of  same  will  receive  the  direct  impact  of  the  dust. 
Cloth  bags  or  metal  screens  if  used  in  this  separator  shall  be  so 
placed  that  nothing  but  the  very  lightest  of  the  dust  can  lodge 
thereon,  and  that  same  may  be  easily  cleaned  without  dismantl- 
ing the  separator.    It  must  be  so  constructed  that  it  shall  inter- 
cept not  less  than  95%  of  the  dust  entering  same. 

38a.  Separator  tank   shall  be  constructed  with  steel  shells, 
with  either  cast  iron  or  steel  heads,  and  be  fitted  with  suitable 


SPECIFICATIONS  199 

bases  or  floor  stands  for  support  and  proper  openings  for  clean- 
ing same.  Separator  shall  be  fittted  with,  iron-column  mercury 
gauge  reading  50%  in  excess  of  operating  vacuum. 

39.  Pipe  Lines.  All  pipe  lines  shall  be  of  the  sizes  and  run 
as  indicated  on  drawings. 

40.  Pipes.  All  pipe  conveying  air  is  to  be  standard  black 
wrought-iron    or   mild-steel   screw-jointed   pipe,    and   is   to    be 
smooth  inside,  free  from  dents,  kinks,  fins,  or  burs.     Ends  of 
pipe  to  be  reamed  to  the  full  inside  diameter  and  beveled.    Bent 
pipe  to  be  used  in  mains  where  necessary  'and  where  shown  on 
plans. 

41.  Care  must  be  taken  in  erecting  pipe  to  maintain  as  near- 
ly as  possible  a  smooth,  uniform  bore  through  all  pipe  and 
fittings. 

42.  Fittings.  All  fittings  to  be  tough  gray  cast  iron,  free  from 
blowholes  or  other  defects;  smooth  castings  in  all  cases. 

43.  All  fittings  on  vacuum  lines  must  have  inside  diameter 
through  body  of  same  size  as  pipe  bore,  and  all  fins,  burs,  or 
rough  places  must  be  removed. 

44.  Fittings  on  vacuum  lines   are  to  be  black   or  may  be 
galvanized. 

45.  Where  space  permits,  all  tees  and  elbows  must  have  a 
radius  at  center  line  of  not  less  than  3  in. 

46.  Horizontal  overhead  pipes  to  be  supported  with  substan- 
tial pipe  hangers  spaced  not  more  than  10  ft.  apart. 

47.  The  hangers  must  have  an  approved  form  of  adjustment 
and  the  instructions  of  the  superintendent  in  regard  to  securing 
hangers   to    floor  construction,    etc.,    above  must   be   carefully 
followed. 

48.  Where  exposed  pipes  pass  through  walls  or  floors  of  fin- 
ished rooms  they   must  be  fitted  with   cast-iron   nickel-plated 
plates. 

49.  Clean-Out  Plugs.  Brass  screw-jointed  clean-out  plugs  are 
to  be  provided  in  lines   at  all  turns  where  indicated  on  the 
drawing.     The  clean-out  plugs  to  be  2  in.  diameter,  except  in 
the  1^2 -in.  lines,  where  clean-outs  are  to  be  same  diameter  as 
the  lines. 

50.  Exhaust   Connection.  Exhaust  pipe  from   the   exhauster 


200  VACUUM    CLEANING    SYSTEMS 

is  to  be  run  up  to  the  basement  ceiling  and  along  same  into  the 
smoke  breeching  beyond  damper  as  directed. 

51.  Sweeper  Inlets.  The  following  number  of  inlets  are  to  be 
provided:    Subbasement          ,  basement  ,  first  story  , 
second  story          ,  attic 

52.  The  sweeper  inlets  are  to  be  fitted  with  hinged  covers  or 
caps  with  rubber  gaskets  arranged  to  be  self-closing  when  hose 
is  removed,  and  those  in .  corridors  and  lobby  'arranged  to  be 
opened  with  a  key. 

53.  Inlets  coming  through  finished  walls  or  partitions  are 
to  be  flusfa  pattern. 

54.  Inlets  on  risers  run  exposed  against  walls  are  to  be  set 
close  up  against  bead  of  fittings. 

55.  If  contractor   desires  to   use   other  form   of   connection 
than  above  described  which,  is  equally  satisfactory,  same  must 
be  submitted  to  the  Architect  for  approval  after  award  of  the 
contract. 

56.  In  this  specification  the   word   "  renovator"   is  used   to 
mean  that  portion  of  the  tool  which  is  in  contact  with  the  sur- 
faces cleaned;  the  word  "stem,"  that  portion  connecting  the 
renovator  -and  hose;  the  word  "cleaner"  is  used  to  mean  a 
complete  cleaning  tool. 

57.  The  following  cleaning  tools  are  to  be  furnished: 

One  carpet  renovator,  with  cleaning  slot  ^  in-  by  12  in.  long. 

One  bare  floor  renovator,  12  in.  long,  with  curved  felt-cov- 
ered face. 

One  wall  renovator,  12  in.  long,  with  cotton  flannel  curved 
face. 

One  upholstery  renovator,  with  slot  l/4  in.  by  4  in. 

One  corner  cleaner. 

One  radiator  cleaner. 

One  hat  brush. 

One  long  curved  stem  about  5  ft.  long. 

One  extension  tube  about  5  ft.  long. 

58.  The  renovators  for  carpets,  bare  floors  and  walls  to  be 
arranged  with  adjustable  swivel   joint,   so  that  same  can   be 
operated  at  an  angle  w.ith  stem  from  45°  for  regular  use  to  an 
angle  of  about  80°  for  use  under  or  back  of  furniture  and  other 
similar  places.     This  movable  joint  to  be  so  arranged  that  lips 


SPECIFICATIONS  201 

of  cleaning  tool  will  always  remain  in  contact  with  surface 
cleaned,  and  constructed  so  that  fitted  surfaces  >are  not  exposed 
to  dust,  and  the  air  currents  when  deflected  to  impinge  only 
upon  surfaces  which  are  of  heavy  metal  and  where  such  wear 
as  occurs  will  not  affect  the  operation  and  handling  of  the  tool. 

59.  All  renovators  -and  stems  are  to  be  as  light  as  is  consis- 
tent with  strength  and  ability  to  withstand  cutting  action  of 
dust. 

60.  The  lips  of  carpet  renovators  and  upholstery  cleaner  to 
be  of  such  proportions  and  form  as  will  prevent  injury  to  the 
fabric,  and  such  widths  as  will  reduce  to  a  minimum  the  stick- 
ing of  renovator  face  to  the  material  being  cleaned. 

61.  Stems  to  be  not  less  than  1  in.  outside  diameter.     Air 
passages  in  swivels  to  be  same  diameter  as  inside  of  stem.    Stem 
for  use  with  floor  renovators  shall  be  curved  near  upper  end  to 
form  handle  and  provided  with  swivel  to  permit  hose  hanging 
vertical. 

62.  Stems  to  be  drawn-steel  or  brass  tubing,  not  less  than 
No.  21  United  States  standard  gauge  thick  if  steel  and  not  less 
than  No.  16  Brown  &  Sharpe  gauge  thick  if  brass. 

63.  Carpet  renovators  to  be  made  preferably  of  pressed  steel, 
as  light  as  possible,  or  may  be  made  of  oast  iron,  brass  or 
aluminum  with  iron  wearing  face. 

64.  Bare  floor  renovators  shall  have  renewable  elastic  wear- 
ing face  curved  in  direction  of  motion  when  cleaning. 

65.  All  renovators  and  brushes  must  be  provided  with  proper 
rubber  or  other  approved  buffers  to  prevent  marring  the  wood- 
work. 

66.  Upholstery  cleaners  are  to  have  inlet  slots  or  openings 
of  such  size   and  form   as  to   absolutely  prevent  drawing   in 
loose  covering  of  furniture. 

67.  Upholstery  and  corner  cleaners  are  not  to  be  arranged 
for  use  with  stems,  but  are  to  have  their  own  handles  perma- 
nently attached  and  be  provided  with  hose  couplings. 

68.  All  metal  parts  of  renovators  and  stems  are  to  be  fin- 
ished, and  all  except  aluminum  parts  nickel  plated. 

69.  Hose.  Furnish  75  ft.  cleaning  hose  in  three  25-ft.  lengths. 

70.  The  hose  to  be  1^  in-  inside  diameter  best  quality  rubber 


202  VACUUM  CLEANING  SYSTEMS 

hose,  reinforced  in  best  manner  to  absolutely  prevent  collapse 
at  highest  vacuum  obtainable  with  the  exhauster  furnished  and 
to  prevent  collapse  if  stepped  on.  Weight  of  hose  to  be  not  over 
12  oz.  per  linear  foot. 

71.  Couplings  for  hose  to  be  either  slip,  bayonet-lock  or  all- 
rubber  type,  with  smooth  bore  of  practically  same  diameter  as 
inside  of  hose.     The  couplings  to  have  least  possible  projection 
outside  of  hose  dimensions  and  be  well  rounded,  so  as  not  to 
injure  floors,  doors,  furniture,  etc. 

72.  Bayonet  joints  may  have  packing  washer,  and  slip  joints 
to  have  permanent  steel  pieces  on  ends  of  hose  and  brass  slip 
coupler.    All  ends  of  hose  at  couplings  to  have  outside  ferrules 
securely  fastened  in  place,  or  pure  gum  ends  glued  to  coupling. 
Simple  conical  slip  joints  slipped  into  ends  of  hose  without  fer- 
rules will  not  be  acceptable.    All  joints  must  fit  together  so  that 
they  will  not  be  readily  pulled  apart. 

73.  Tests.  All  piping  to  be  tested  writh  air  pressure  equal  to 
5  in.  mercury  before  being  concealed  in  walls  and  other  spaces. 
Mercury  must  not  fall  more  than  y\  in.  in  one-half  hour. 

74.  On  completion  of  plant  the  pump  will  be  operated  with 
all  outlets  closed  and,  under  these  conditions,  there  must  be  an 
interval  of  not  less  than  10  min.  between   the  stopping  and 
starting  of  the  motor  by  the  automatic  control,  if  pump  system 
is  used.     And  if  fan  system  be  used,  the  power  required  to 
operate  the  exhauster  must  not  be  more  than  65%  of  that  re- 
quired in  capacity  test. 

75.  To  test  the  capacity  of  the  separator,  a  mixture  contain- 
ing 6  Ibs.  of  sand,  passed  through  a  50-mesh  screen,  3  Ibs.  of 
common  wheat  flour  and  16  Ibs.  of  Portland  cement  shall  be 
spread  over  50  sq.  ft.  of  floor  and  picked  up  with  a  renovator 
attached  to  the  end  of  50  ft.  of  1*4 -in.  hose.    The  machine  shall 
be  stopped  and  the  material  removed  from  the  separator  spread 
on  floor  and  picked  up.     This  procedure  shall  be  repeated  until 
the  material  has  been  handled  four  times.     If  the  separator 
contains  a  bag,  the  same  must  not  be  disturbed  until  after  com- 
pletion  of   the    capacity   test,    which   will  be   made  with   the 
material  in  place  in  separator,  after  being  picked  up  the  fourth 
time. 


SPECIFICATIONS  203 

After  completion  of  capacity  test,  the  contents  of  separator 
shall  be  weighed  and  if  same  be  a  partial  separator  it  must 
contain  95%  of  the  material  picked  up.  If  a  displacement 
machine  is  used  as  a  vacuum  producer,  the  separator  must  pre- 
vent the  passage  of  any  dust  through  separator,  which  will  be 
determined  by  holding  a  dampened  cloth  over  pump  outlet 
during  test  of  apparatus.  Said  cloth  must  not  show  any  dust 
lodged  thereon  at  end  of  /test. 

76.  To  test  the  capacity  of  the  plant  a  standard  vacometer, 
attached  to  the  end  of  75  ft.  of  cleaning  hose  shall  show  a 
vacuum  of  2  in.  mercury  with  ^-in.  diameter  orifice  open. 

77.  Test  of  Cleaning  Tools.  The  plant  shall  be  operated  by  the 
Contractor  in  the  presence  of  the  Architect's  representative,  and 
a  test  made  of  each  kind  of  cleaning  tool  furnished.    The  tool 
shall  be  attached  to  a  50-ft.  length  of  hose  attached  to  an  outlet 
selected  by  the  Architect's  representative,   and   under  normal 
working  conditions   each  tool   must  satisfactorily   perform   the 
work  for  which   it   was  designed.     Dust   and   surfaces   to   be 
cleaned  shall  be  furnished  by  the  contractor. 

78.  Painting.  After  the  completion  of  the  specified  tests,  all 
exposed  iron  work  except  galvanized  iron  or  tinned  work  in 
connection  with   this  apparatus,   not  specified   to  be  otherwise 
finished,  shall  be  primed  with  paint  suitable  for  surfaces  covered, 
and  then  given  two  additional  coats.   Machinery  shall  be  painted 
as  already  specified,  and  all  other  work  shall  be  given  finishing 
tints  as  selected  or  approved  by  the  architect.    Black  iron  pipe, 
etc.,  shall  be  given  two  coats  lead  and  oil  of  tint  directed. 

Modifications  of  Specifications  when  Alternating  Current 
is  Available. — When  alternating  current  is  available,  instead 
of  direct,  modify  specifications  as  follows : 

23.  Motor  to  be  wound  for   ....   volts,    .  .  .  .cycle,    .  .  .  .phase 
alternating  current. 

24.  Motor  to  have  rotor  of  the  squirrel  cage  type. 
Omit  25,  26  and  27. 

28.  To  remain  as  for  direct  current. 

29.  There  must  be  an  insulation  between  the  starter  or  pri- 
mary windings  and  the  frame  of  not  less  than  one  megohm. 

30.  31,  and  32.  Same  as  for  direct  current. 


204  VACUUM  CLEANING  SYSTEMS 

33.  Tablet.  Furnish  and  mount  where  directed  a  polished 
slate  tablet  having  mounted  thereon  a  30  ampere,  250  volt, 
....  pole  knife  switch  with  enclosed  indicating  fuses  and;  if 
displacement  type  exhauster  is  furnished,  an  automatic  starter 
of  the  ''across  the  line"  type,  operated  by  vacuum  in  the 
separator  which  will  stop  motor  when  the  vacuum  in  the  sepa- 
rator rises  2  in.  above  that  required  to  meet  test  conditions,  and 
start  exhauster  when  vacuum  reaches  working  range. 

CLASS  2 

PLANT  FOR  LARGE  OFFICE  BUILDING  HAVING   PIPE  LINES  OF 
MODERATE  LENGTH. 

1.  Same  as  for  Class  1. 

2.  Omit  centrifugal  fan. 

3  to  9.  Same  as  for  Class  1. 

Omit  10  to  13. 

14  and  16.  Same  as  for  Class  1. 

15.  Omit  centrifugal  fan. 

Omit  17  and  18. 

18a.  Base  Plate,  Foundation,  etc.  Provide  suitable  base 
plate  to  rigidly  support  the  exhauster  and  its  motor  as  a  unit, 
which  shall  be  large  enough  to  catch  all  drip  of  water  or  oil. 
Provide  a  raised  margin  and  pads  for  feet  of  exhauster  frame, 
motor,  and  anchor  bolts,  high  enough  to  prevent  any  drip  from 
getting  into  the  foundation  or  on  the  floor. 

18b.  Provide  suitable  foundation  of  brick  or  concrete,  to 
which  the  base  plate  shall  be  firmly  anchored.  The  foundation 
shall  be  built  on  top  of  the  cement  floor  of  the  basement,  which 
shall  be  picked  to  afford  proper  bond  for  the  foundation. 

18c.  Construct  the  foundation  of  such  a  height  as  to  bring 
the  working  parts  of  the  machine  -at  the  most  convenient  level 
for  operating  purposes.  Exposed  parts  of  the  foundation  to  be 
faced  with  best  grade  white  enameled  brick.  If  the  base  plate 
does  not  cover  the  foundation,  the  exposed  top  surface  is  to  be 
finished  with  enameled  brick,  using  bull-nose  brick  on  all  edges 
and  corners. 

19  to  23.  Same  as  for  Class  1. 

23a.  The  guaranteed  efficiency  of  motor  shall  not  be  less 
than  78%  at  half  load  and  not  less  than  84%  at  full  load. 

24  to  32.  Same  as  for  Class  1. 


SPECIFICATIONS  205 

32a.  Motor  shall  be  subject  to  shop  test  to  determine  effi- 
ciency, heating,  insulation,  etc.  Manufacturer's  certified  test 
sheets  of  motor  giving  all  readings  taken  during  shop  tests, 
together  with  calculated  results,  must  be  submitted  to  the  Archi- 
tect for  approval  before  motor  is  shipped  from  factory. 

33.  Rheostat.  Furnish    and    install    where    shown,    upon    a 
slate   panel    hereinafter  specified,  a  starting  rheostat  of  proper 
size  and  approved  made,  designed  for  the  particular  duty  it  has 
to  perform.     It  must  have  an  automatic  no-voltage  and  over- 
load release.    All  resistance  for  rheostat  is  to  be  placed  on  the 
back  of  the  tablet.     Contacts  must  project  through  board  to 
front  side.    All  moving  parts  must  be  on  front  of  board. 

33a.  Tablet.  Furnish  and  place  where  shown,  a  slate  tab- 
let not  less  than  y$  in.  thick,  supported  by  a  substantial  angle 
iron  frame,  so  placed  that  there  will  be  a  space  of  not  less  than 
4  in.  between  the  wall  and  back  of  resistance.  Mount  on  this 
tablet  one  double-pole,  250-volt  knife  switch,  with  two  250-volt 
inclosed  fuses  and  one  starting  rheostat,  as  specified  hereinbe- 
fore. The  connections  shall  be  on  the  back  of  the  tablet.  The 
space  between  the  column  and  the  tablet  shall  be  inclosed  with 
a  removable  diamond-mesh  grill  of  No.  10  iron  wire  in  channel 
frame. 

34,  35,  36.  Same  as  for  Class  1. 

36a.  Automatic  Control.  Suitable  means  shall  be  provided  in 
connection  with  the  rotary  exhausters  that  will  maintain  the 
vacuum  in  the  separators  within  the  limit  of  the  machine  at 
point  found  to  be  most  desirable,  irrespective  of  the  number  of 
sweepers  in  operation. 

36b.  Controller  shall  consist  of  a  suitable  means  provided  in 
the  exhauster,  or  as  an  attachment  thereto,  which  will  auto- 
matically throw  the  exfhauster  out  of  action  by  admitting  atmos- 
pheric pressure  to  the  exhauster  only,  but  not  to  the  system 
whenever  the  vacuum  in  the  separators  rises  above  the  point 
considered  desirable,  and  throw  the  exhauster  into  action  when 
the  vacuum  falls  below  the  established  lower  limit. 

36c.  Vacuum  Breaker.  In  addition  to  the  controlling  devices 
above  specified  there  shall  be  placed  in  the  suction  pipe  to  the 
exhauster  an  approved  positive-acting  vacuum  breaker  having 


206  VACUUM  CLEANING  SYSTEMS 

opening  equivalent  to  the  area  of  1-in.  diameter  pipe  and  set 
to  open  at  10  inches  vacuum. 

(If  plant  is  to  be  run  for  long  periods  without  much  load,  as 
in  a  hotel,  omit  36a,  b,  c,  and  substitute)  : 

36d.  Automatic  Control.  An  approved  type  of  controller  for 
maintaining  practically  a  constant  vacuum  by  varying  the 
speed  of  the  motor  driving  exhauster  arranged  to  permit  the 
operation  of  the  motor  continuously  at  any  speed  between  full 
speed  and  stop,  so  long  as  there  be  no  change  in  vacuum  and 
which  will  increase  speed  whenever  vacuum  falls  and  reduce 
speed  whenever  vacuum  rises,  must  be  provided. 

37.  Dust  Separator.  There  shall  be  one  dry  separator  located 
where  shown  on  plans,  having  a  volume  of  not  less  than  3  cu.  ft, 
for  each  sweeper  of  plant  capacity. 

38.  The  interior  arrangement  of  the  separator  shall  be  such 
that  no  part  of  same  will  receive  the  direct  impact  of  the  dust. 
Cloth  bags  or  metal  screens,   if  used  in  this  separator,  shall 
be  so  placed  that  nothing  but  the  very  lightest  of  the  dust 
can  lodge  thereon,  and  that  same  may  be  easily  cleaned  without 
dismantling  the  separator.     It  must  be  so  constructed  that  it 
will  intercept  all  of  the  dust  entering  same. 

38a  to  56.  Same  as  for  Class  1. 

56a.  Tool  Cases.  Furnish  approved  hardwood  cabinet-fin- 
ished cases  for  cleaning  tools.  Each  case  to  be  made  as  light 
as  possible  and  of  convenient  form  for  carrying  by  hand  and 
provided  with  a  complete  set  of  cleaning  tools,  each  securely 
held  in  its  proper  place,  and  fitted  with  lock  and  key,  clamps, 
and  conveniently  arranged  handles. 

57.  Each  case  shall  contain  the  following: 

One  carpet  renovator,  with  slot  ^4  in-  D7  15  in. 

One  bare  floor  renovator,  15  in.  long,  with  curved  felt-cov- 
ered face. 

One  wall  brush,  with  skirted  bristles,  12  in.  long  and  l/2  in. 
wide. 

One  hand  brush,  with  hose  connections  at  end,  8  in.  long, 
2  in.  wide. 

One  4-in.  round  brush  for  relief  work. 


SPECIFICATIONS  207 

One  upholstery  renovator. 

One  corner  cleaner. 

One  radiator  tool. 

One  curved  stem  about  5  ft.  long. 

One  extension  tube  5  ft.  long. 

At  least  one  hat  brush  with  the  system. 

58  to  64.  Same  as  for  Class  1. 

64a.  All  brushes  to  be  of  substantial  construction,  with  best 
quality  bristles  set  in  close  rows  and  as  thick  as  possible,  skirted 
with  rubber,  leather,  or  chamois  skin,  so  that  all  air  entering 
renovator  will  pass  over  surface  being  cleaned. 

65  to  68.  Same  as  for  Class  1. 

69.  Hose  Racks.  Furnish  and  properly  secure  in  place,  where 
directed,  ....  hose  racks  in  basement,  ....  each  in  first  and 
second  stories  ( .  . .  .  racks  in  all).  The  racks  to  be  constructed 
of  cast  iron,  galvanized  or  enamel  finish,  and  each  rack  to  be 
suitable  for  holding  75  ft.  of  hose  of  required  size. 

69a.  Hose.  There  must  be  furnished  with  each  hose  rack  75 
ft.  of  noncollapsible  hose  in  three  25-ft.  lengths. 

70  to  73.  Same  as  for  Class  1. 

74.  On  completion  of  the  plant  the  pump  will  be  operated 
with  all  outlets  closed,  and,  under  this  condition,   the  power 
consumption   must   not   be    more   than   50%    of   that   required 
under  test  conditions. 

75.  Test  of  Separators.  At   each  of points,   near out- 
lets on  different  risers  selected  by  the  architect's  representa- 
tive, the  contractor  shall  furnish  and  spread  on  the  floor,  evenly 
•covering  an  -area  of  approximately  50  sq.  ft.  for  each  outlet,  a 
mixture  of  6  Ibs.  of  dry  sharp  sand  that  will  pass  a  50-mesh 
screen,  3  Ibs.  of  fine  wheat  flour  and  6  Ibs.  of  Portland  cement. 

75b.  Fifty  feet  of  hose  shall  be  attached  to  each  of  the — 
•outlets,  and  the  surfaces  prepared  for  cleaning  shall  be  cleaned 
simultaneously  by  operators  provided  by  the  contractor  until 
all  of  the  sand,  flour  and  Portland  cement  has  been  taken  up, 
when  the  exhauster  shall  be  stopped  and  the  dirt  removed  from 
the  separator  and  spread  on  the  floor  again,  and  the  operation 


208  VACUUM  CLEANING  SYSTEMS 

of  cleaning  repeated  until  the  mixture  has  been  handled  by  the 
apparatus  four  times. 

The  bag  contained  in  the  separator  must  not  be  disturbed 
until  after  completion  of  the  capacity  test,  which  will  be  made 
with  material  in  place  in  the  separator  after  being  picked  up 
the  fourth  time.  After  completion  of  the  capacity  test  the 
contents  of  separator  will  be  removed.  During  test  of  sepa- 
rators a  dampened  cloth  will  be  held  over  the  exhaust  from 
pump.  If  such  cloth  indicates  dirt  passing  through  the  sepa- 
rator, same  will  be  rejected. 

76.  To  test  the  capacity  of  the  plant,  one  hose  line  100  ft. 
long  shall  be  attached  to  inlet  farthest  from  the  separator  with 

standard  vacometer,  with  ^2 -in.  opening  in  end  of  hose 

hose  lines  shall  be  attached  to  other  outlets,  each  with  50  ft. 
hose  and  vacometers  in  end  of  hose,  ....  vacometers  having 
^2 -in.  opening  'and  ....  vacometers  having  %-in  opening. 
Under  these  conditions  4  in.  mercury  must  be  maintained  in 
vacometer  at  end  of  100  ft.  of  hose. 

77  and  78.  Same  as  for  Class  1. 

Modifications  of  Specifications  when  Alternating  Current 
is  Available. — When  alternating  current  is  available,  instead  of 
direct,  modify  specifications  as  follows: 

23.  Motor  to  be  wound  for  ....  volts,  ....  cycle,  ....  phase 
alternating  current. 

23a.  Bidders  must  name  efficiency  and  power  factor  of  motor 
at  onejhalf  and  full  load. 

24.  Motor  to  have  phase-wound  rotor  with  collector  rings  for 
insertion  of  starting  resistance. 

Omit  25,  26  and  27. 

28.  Same  as  for  direct  current. 

29.  There  must  be  an  insulation  between  the  starter  or  pri- 
mary windings  and  the  frame  of  not  less  than  one  megohm. 

30.  31,  32,  32a.  Same  as  for  direct  current. 

33.  Rheostat.  Furnish  and  install  an  approved  hand-starting 
rheostat  for  inserting  resistance  in  rotor  circuit  in  starting,  of 
proper  size  to  insure  the  starting  of  motor  in  not  exceeding 
15  seconds  without  overheating. 


SPECIFICATIONS  209 

33a.  Same  as  for  direct  current,  except  that  switch  must  be 
either  three-  or  four-pole,  according  to  current  available. 
Omit  36d  with  alternating  current  machine. 

CLASS  3 

LARGE  INSTALLATION  WITH  UNUSUALLY  LONG  PIPE  LINES. 

1.  Same  as  for  Class  1. 

2.  Exhauster  shall  be  of  the  reciprocating  piston  type. 

3.  The  piston  type  of  exhauster  shall  be  double  acting  and 
so  designed  that  the  cylinder  clearance  shall  be  reduced  to  a 
minimum,  or  suitable  device  shall  be  employed  to  minimize  the 
effect  of  large  clearance. 

4.  The  induction  and  eduction  valves  may  be  either  poppet, 
rotary,   or  semi-rotary,   and  shall  operate  smoothly  and  noise- 
lessly. 

5.  The  piston  packing  shall  be  of  such  character  as  to  be 
practically  air  tight  under  working  conditions  and  constructed 
so  that  it  will  be  set  out  with  its  own  elasticity  without  the  use 
of  springs  of  any  sort.     If  metallic  rings  are  used,  they  must 
fill  the  grooves  in  which  they  are  fitted,  both  in  width  and 
depth,  and  must  be  concentric;  that  is,  of  the  same  thickness 
throughout.     The  joint  in  the  ring  or  rings  to  be  lapped  in 
width  but  not  in  thickness,  and  if  more  than  one  ring  is  used 
they  are  to  be  placed  and  doweled  in  such  position  in  their 
respective  grooves  so  that  the  joints  will  be  at  least  one-fourth 
of  the  circumference  apart. 

6.  The  piston  shall  have  no  chamber  or  space  into  which  air 
may  leak  from  either  side  of  the  piston.     All  openings  into 
the  body  of  the  piston  must  be  tightly  plugged  with  cast-iron 
plugs. 

7.  The  piston  rod  stuffing  box  to  be  of  such  size  and  depth 
that  if  soft  packing  is  used  it  can  be  kept  tight  without  undue 
pressure  from  the  gland.     If  metallic  packing  is  used,  it  must 
be  vacuum  tight  without  undue  pressure  on  the  rod.     Proper 
means  shall  be  provided  for  the  continuous  lubrication  of  the 
piston  rod. 

8.  The  exhauster  of  the  piston  type  shall  be  fitted  with  an 
approved  cross-head  suitably  attached  to  the  piston   rod ;  ma- 


210  VACUUM  CLEANING  SYSTEMS 

chines  having  an  extended  piston  rod  for  guide  purposes  will 
not  be  acceptable. 
Omit  9  to  13. 

14.  Same  as  for  Class  1. 

15.  Reciprocating   piston   exhauster  shall   be   provided   with 
the  necessary  devices  for  the  removal  of  the  heat  generated  by 
friction  and  compression,  that  shall  prevent  the  temperature  of 
cylinders  or  eduction  chambers  rising  more  than  100°  F.  above 
the  surrounding  atmosphere  after  two  hours'  continuous  oper- 
ation under  full-load  conditions. 

16.  Speed.  Reciprocating  exhauster  with  poppet  valves  shall 
operate  at  an  average  piston  speed  not  exceeding  200  ft.  per 
minute,  with  rotary  valves  not  exceeding  300  ft.  per  minute. 

Omit  17  and  18. 

18a.  Ease  Plate,  Foundation,  etc.  Provide  suitable  base  plate 
to  rigidly  support  the  exhauster  and  its  motor  as  a  unit,  which 
shall  be  large  enough  to  catch  all  drip  of  water  or  oil.  Provide 
a  raised  margin  and  pads  for  feet  of  exhauster  frame,  motor, 
and  anchor  bolts,  high  enough  to  prevent  any  drip  from  get- 
ting into  the  foundation  or  on  the  floor. 

18b.  Provide  suitable  foundation  of  brick  or  concrete,  to 
which  base  plate  shall  be  firmly  anchored.  The  foundation  shall 
be  built  on  top  of  the  cement  floor  of  the  basement,  which  shall 
be  picked  to  afford  proper  bond  for  the  foundation. 

18c.  Construct  the  foundation  of  such  a  height  as  to  bring 
the  working  parts  of  the  machine  at  the  most  convenient  level 
for  operating  purposes.  Exposed  parts  of  the  foundation  to  be 
faced  with  best  grade  white  enameled  brick.  If  the  base  plate 
does  not  cover  the  foundation,  the  exposed  top  surface  is  to  be 
finished  with  enameled  brick,  using  bull-nose  brick  on  all  edges 
and  corners. 

19  to  23.  Same  as  for  Class  1. 

23a.  The  guaranteed  efficiency  of  motor  shall  not  be  less  than 
80%  at  half  load  and  not  less  than  85%  at  full  load. 

24  to  32.  Same  as  for  Class  1. 

32a.  Motor  shall  be  subject  to  shop  test  to  determine  effi- 
ciency, heating,  insulation,  etc.  Manufacturers'  certified  test 
sheets  of  motor,  giving  all  readings  taken  during  shop  test,  to- 


SPECIFICATIONS  211 

gether  with  calculated  results,  must  be  submitted  to  the  Archi- 
tect for  approval  before  motor  is  shipped  from  factory. 

33.  Rheostat.    Furnish    and    install    where    shown,    upon    a 
slate  panel  hereinafter  specified,  a  starting  rheostat  of  proper 
size  and  approved  make,  designed  for  the  particular  duty  it  has 
to  perform.     It  must  liave  an  automatic  no-voltage  and  over- 
load release.     All  resistance  for  rheostat  is  to  be  placed  on  the 
ba<ck  of  the  tablet.     Contacts  must  project  through  board  to 
front  side.     All  moving  parts  must  be  on  front  of  board. 

33a.  Tablet.  Furnish  and  place  where  shown,  a  slate  tab- 
let, not  less  than  %  in.  thick,  supported  by  a  substantial  angle 
bar  frame,  so  placed  that  there  will  be  a  space  of  not  less  than 
4  in.  between  the  wall  and  back  of  resistance.  Mount  on  this 
tablet  one  double-pole,  250-volt  knife  switch,  with  two  250-volt 
inclosed  fuses  and  one  starting  rheostat,  as  specified  herein- 
before. The  connections  shall  be  on  the  back  of  the  tablet. 
The  space  between  the  column  and  the  tablet  shall  be  inclosed 
with  a  removable  diamond-mesh  grill  of  No.  10  iron  wire  in 
channel  frame. 

34,  35  and  36.  Same  as  for  Class  1. 

37.  Dust  Separators.  There  shall   be   one   dry  and   one  wet 
separator  located  where  shown  on  drawings.     Each  separator 
shall  have  a  volume  of  3  cu.  ft.  for  each  renovator  of  plant 
capacity. 

38.  The   separator  first   receiving  the    dust  shall   be  a   dry 
separator,  the  interior  arrangement  of  which  shall  be  such  that 
no  part  of  same  shall  receive  the  direct  impact  of  the  dust. 
No  screens  or  cloth  bags  shall  be  used  in  this  separator  and  it 
must  be  so  constructed  that  it  will  intercept  95%  of  the  dust 
entering  same. 

38a.  The  second  separator  must  be  a  wet  separator  which 
may  be  contained  in  the  base  of  the  machine  or  consist  of  a 
separate  tank. 

38b.  Wet  separators,  whether  separate  from  or  integral  with 
the  base  of  the  machine,  must  be  provided  with  an  attachment 
which  will  positively  mix  the  air  and  water,  thoroughly  break 
up  all  bubbles,  separate  the  water  from  the  air,  and  prevent 
any  water  entering  the  exhauster  cylinder. 


212  VACUUM  CLEANING  SYSTEMS 

38c.  Suitable  means  must  be  provided  to  automatically  equal- 
ize the  vacuum  between  wet  and  dry  separators  upon  the  shut- 
ting down  of  the  exhauster. 

38d.  The  separators  must  be  provided  with  suitable  openings 
for  access  to  the  interior  for  inspection  and  cleaning,  and  the 
interior  arrangement  of  the  separators  must  be  such  that  they 
may  be  readily  cleaned  without  dismantling. 

38e.  All  parts  of  the  wet  separator  tank  not  constructed  of 
non-corrosive  metal  must  be  thoroughly  tinned  or  galvanized 
both  inside  and  outside.  The  interior  of  the  wet-  separator 
formed  in  base  of  exhauster  shall  be  painted  with  at  least  two 
coats  of  asphalt  varnish  or  other  paint  suitable  to  prevent  the 
corrosion  of  same. 

38f.  Separators  must  be  provided  with  all  necessary  valves 
or  other  attachments  for  successful  operation,  including  a  sight 
glass  for  the  wet  separator,  through  which  the  interior  of  the 
same  may  be  observed,  and  an  iron-case  mercury  column  read- 
ing 50%  in  excess  of  operating  vacuum,  attached  to  the  dry 
separator  first  receiving  the  dust. 

38g.  The  wet  separator  shall  be  properly  connected  to  water 
supply  where  directed  and  discharge  to  sewer  where  shown  on 
plans. 

38h.  A  running  trap  with  clean-out  shall  be  installed  in  the 
waste  line. 

39  to  41.  Same  as  for  Class  1. 

41a.  Waste  and  water  pipe,  in  connection  with  wet  separator 
and  jacket,  except  waste  pipe  below  basement  floor,  to  be  stand- 
ard galvanized  wrought-iron  pipe  or  steel  screw-jointed  pipe 
free  from  burs.  Waste  pipe  below  the  basement  floor  is  to  be 
best  grade,  ' '  extra  heavy ' '  cast-iron  pipe,  with  •  lead-calked 
joints. 

42  to  45.  Same  as  for  Class  1. 

45a.  Fittings  on  water  lines  to  be  standard  galvanized  beaded! 
fittings. 

45b.  Fittings  on  waste  line  above  basement  floor  line  to  be 
galvanized  recessed  screw- jointed  drainage  fittings  and  those 
below  basement  floor  to  be  "extra  heavy"  cast-iron  with  hub 
joints. 


SPECIFICATIONS  213 

46  to  50.  Same  as  for  Class  1. 

50a.  The  exhaust  pipe  is  to  be  fitted  with  an  approved  first- 
class  exhaust  muffler  not  less  than  12  in.  in  diameter  and  60  in. 
high,  closely  riveted  and  constructed  of  galvanized  iron  not  less 
than  %  in.  thick,  and  in  event  an  exhauster  requiring  lubrica- 
tion is  furnished,  this  muffler  is  to  be  arranged  so  that  it  will 
also  be  an  efficient  oil  separator.  Drip  connection  to  be  arranged 
at  bottom  of  muffler. 

51  to  56.  Same  as  for  Class  1. 

56a.  Tool  Cases.  Furnish  approved  hardwood  cabinet- 
finished  cases  for  cleaning  tools.  Each  case  to  be  made  as  light 
as  possible  and  of  convenient  form  for  carrying  by  hand  and 
provided  with  a  complete  set  of  cleaning  tools,  each  securely 
held  in  its  proper  place,  and  fitted  with  lock  and  key,  clamps 
and  conveniently  arranged  handles. 

57.  Each  case  shall  contain  the  following: 

One  carpet  renovator,  with  slot  l/\.  in.  by  12  in. 

One  bare  floor  renovator  12  in.  long,  with  curved,  felt-cov- 
ered face. 

One  wall  brush,  with  skirted  bristles,  12  in.  long  and  l/2  in. 
wide. 

One  hand  brush,  with  hose  connection  at  end,  8  in.  long  and 
2  in.  wide. 

One  4-in.  round  brush  for  relief  work. 

One  upholstery  renovator. 

One  corner  cleaner. 

One  radiator  tool. 

One  curved  stem  about  5  ft  long. 

One  straight  extension  stem  5  ft.  long. 

At  least  one  hat  brush  with  the  system. 

58  to  64.  Same  as  for  Class  1. 

64a.  All  brushes  to  be  of  substantial  construction,  with  best 
quality  bristles  set  in  close  rows  and  as  thick  as  possible,  skirted 
with  rubber,  leather,  or  chamois  skin,  so  that  all  air  entering 
renovator  will  pass  over  surface  being  cleaned. 

65  to  68.  Same  as  for  Class  1. 

69.  Hose  Racks.  Furnish  and  properly  secure  in  place  where 
directed,  ....  hose  racks  in  basement,  ....  each  in  first  and 


214  VACUUM  CLEANING  SYSTEMS 

second  stories  ( .  . .  .  racks  in  all).  The  racks  to  be  constructed 
of  cast-iron,  galvanized  or  enamel  finish,  and  each  rack  to  be 
suitable  for  holding  75  ft.  of  hose  of  required  size. 

69a.  Hose.  There  must  be  furnished  .with  each  hose  rack  75 
ft.  of  non-collapsible  hose  in  three  25-ft.  lengths. 

70.  Hose  to  be  1  in.  inside  diameter  of  best  quality,  rubber 
hose,  reinforced  in  best  manner  to  absolutely  prevent  collapse 
at  highest  vacuum  obtainable  with  the  exhauster  furnished  and 
to  prevent  collapse  if  stepped  on.     Weight  of  hose  to  be  not 
over  12  oz.  per  linear  foot. 

71,  72  and  73.  Same  as  for  Class  1. 

74.  On  completion  of  the  plant  the  pump  will  be  operated 
with  all  outlets  closed  and,  under  this  condition,   the  power 
consumption  must  not  be  more  than  50%  of  that  required  under 
test  conditions. 

75.  To  test  the  capacity  of  the  plant,    ....   hose  lines  each 
100  ft.  long  will  be  attached  to  outlets  on  the  system  and  each 

hose  fitted  with  a  standard  vacometer vacometers  shall 

have  1/2 -in.  opening  and  ....  vacometers  shall  have  %-in.  open- 
ing.    Under  these  conditions  4  in.  vacuum  must  be  maintained 
at  vacometers  having  l/2  in.  opening. 

75a.  Test  of  Separators.  At  each  of points,  near out- 
lets on  different  risers  selected  by  the  architect's  representative, 
the  contractor  shall  furnish  and  spread  on  the  floor,  evenly  cov- 
ering an  area  of  approximately  50  sq.  ft.  for  each  outlet,  a  mix- 
ture of  6  Ibs.  of  dry  sharp  sand  that  will  pass  a  50-mesh  screen, 
3  Ibs.  of  fine  wheat  flour,  and  1  Ib.  of  finely  pulverized  charcoal. 

75b.  Fifty  feet  of  hose  of  size  required  by  the  system  shall 
be  attached  to  each  of  the outlets,  and  the  surface  or  sur- 
faces prepa-red  for  cleaning  shall  be  cleaned  simultaneously  by 
operators  provided  by  the  contractor  until  all  of  the  sand,  flour 
and  charcoal  has  been  taken  up,  when  the  exhauster  shall  be 
stopped  and  the  dirt  removed  from  the  dry  separator  and  spread 
on  the  floor  again,  and  the  operation  of  cleaning  repeated  until 
the  mixture  has  been  handled  by  the  apparatus  four  times.  If, 
after  thoroughly  flushing  the  system  at  completion  of  above 
run,  any  dust  or  mud  is  found  in  the  cylinder,  ports,  or  valve 


SPECIFICATIONS  215 

chambers  of  the  displacement  exhauster,  or  if  less  than  95% 
of  the  dirt  removed  is  found  in  the  dry  separator,  it  shall  be 
deemed  sufficient  ground  for  the  rejection  of  the  separators. 

76  and  77.  Same  as  for  Class  1. 

Modifications  of  Specifications  when  Alternating  Current 
is  Available. —  When  alternating  current  is  available,  instead 
of  direct,  modify  specifications  as  follows: 

23.  Motor  to  be  wound  for  ....  volts,  ....  cycle,  ....  phase 
alternating  current. 

23a.  Bidders  must  name  efficiency  and  power  factor  of  motor 
at  one-half  and  full  load. 

24.  Motor  to  have   phase-wound   rotor   with   collector   rings 
for  insertion  of  starter  resistance. 

Omit  25,  26  and  27. 

29.  Same  as  for  Class  1,  alternating  current. 

33.  Rheostat.  Furnish  and  install  an  approved  hand-starting 
rheostat  for  inserting  resistance  in  rotor  circuit  in  starting,  of 
proper  size  to  insure  the  starting  of  motor  in  not  exceeding 
15  seconds  without  overheating. 

33a.  Same  as  for  direct  current,  except  switch  must  be  either 
three-  or  four-pole,  according  to  current  available. 

CLASS  4 

LARGE  OR  SMALL  PLANT  WHERE  CARPET  CLEANING  is  OF  SEC- 
ONDARY IMPORTANCE. 

1  to  17.  Same  as  for  Class  1. 

Omit  18. 

18a.  Base  Plate,  Foundation,  etc.  Provide  suitable  base  plate 
to  rigidly  support  the  exhauster  and  its  motor  as  a  unit,  which 
shall  be  large  enough  to  catch  all  drip  of  water  or  oil.  Provide 
a  raised  margin  and  pads  for  feet  of  exhauster  frame,  motor, 
and  anchor  bolts,  high  enough  to  prevent  any  drip  from  getting 
into  the  foundation  or  on  the  floor. 

18b.  Provide  suitable  foundation  of  brick  or  concrete,  to 
which  the  base  plate  shall  be  firmly  anchored.  The  founda- 
tion shall  be  built  on  top  of  the  cement  floor  of  the  basement, 
which  shall  be  picked  to  afford  proper  bond  for  the  foundation. 

18c.  Construct  the  foundation  of  such  a  height  as  to  bring 


216  VACUUM  CLEANING  SYSTEMS 

the  working  parts  of  the  machine  at  the  most  convenient  level 
for  operating  purposes.  Exposed  parts  of  the  foundation  to  be 
faced  with  best  grade  white  enameled  brick.  If  the  base  plate 
does  not  cover  the  foundation,  tire  exposed  top  surface  is  to  be 
finished  with  enameled  brick,  using  bull-nose  brick  on  all  edges 
and  corners. 

19  to  23.  Same  as  for  Class  1. 

23a.  The  guaranteed  efficiency  of  motor  shall  not  be  less  than 
78%  at  half  load  and  not  less  than  84%  at  full  load. 

24  to  32.  Same  as  for  Class  1. 

32a.  Motor  shall  be  subject  to  shop  test  to  determine  effi- 
ciency, heating,  insulation,  etc.  Manufacturers'  certified  test 
sheets  of  motor,  giving  all  readings  taken  during  shop  test, 
together  with  calculated  results,  must  be  submitted  to  the 
Architect  for  approval  before  motor  is  shipped  from  factory. 

33.  Rheostat.  Furnish    and    install    where    shown,    upon    a 
slate  panel  hereinafter  specified,  a  starting  rheostat  of  proper 
size  and  approved  make,  designed  for  the  particular  duty  it 
has  to  perform.     It  must  have  an  automatic  no-voltage   and 
overload  release.     All  resistance  for  rheostat  is  to  be  placed 
on  the  back  of  the  tablet.    Contacts  must  project  through  board 
to  front  side.    All  moving  parts  must  be  on  front  of  board. 

33a.  Tablet.  Furnis  hand  place  where  shown,  a  slate  tab- 
let not  less  than  24  in-  thick,  supported  by  a  substantial  angle 
iron  frame,  so  placed  that  there  will  be  a  space  of  not  less  than 
4  in.  between  the  wall  and  back  of  resistance.  Mount  on  this 
tablet  one  double-pole,  250-volt  knife  switch,  with  two  250-volt 
inclosed  fuses  and  one  starting  rheostat,  as  specified  herein- 
before. The  connections  shall  be  on  the  back  of  the  tablet. 
The  space  between  the  column  and  the  tablet  shall  be  enclosed 
with  a  removable  diamond-mesh  grill  of  No.  10  wire  in  channel 
frame. 

34,  35  and  36.  Same  as  for  Class  1. 

36a.  Automatic  Control.  Suitable  means  shall  be  provided  in 
connection  with  the  rotary  exhauster  that  will  maintain  the 
vacuum  in  the  separators  within  the  limit  of  the  machine  at 
point  found  to  be  most  desirable,  irrespective  of  the  number 
of  sweepers  in  operation. 


SPECIFICATIONS  217 

36b.  Controller  shall  consist  of  a  suitable  means  provided 
in  the  exhauster,  or  as  an  attachment  thereto,  which  will  auto- 
matically throw  the  exhauster  out  of  action  by  admitting 
atmospheric  pressure  to  the  exhauster  only,  but  not  to  the  sys- 
tem ;  whenever  the  vacuum  in  the  separator  rises  above  the  point 
considered  desirable,  and  throw  the  exhauster  into  action  when 
the  vacuum  falls  below  the  established  lower  limit. 

36c.  In  addition  to  control,  a  positive  vacuum  breaker  having 
an  opening  equal  to  1  in.  diameter  pipe  net  for  6  in.  of  mercury, 
must  be  provided  on  separator. 

36d.  If  centrifugal  fan  is  used,  no  control  or  vacuum  breaker 
will  be  required. 

37.  Furnish  one  separator  having  a  cubic  contents  of  4.5  cu. 
ft.  for  each  sweeper  of  plant  capacity. 

38  to  56.  Same  as  for  Class  1. 

56a.  Tool  Cases.  Furnish  approved  hardwood  cabinet-fin- 
ished cases  for  cleaning  tools.  Each  case  to  be  made  as  light 
as  possible  and  of  convenient  form  for  carrying  by  hand  and 
provided  with  a  complete  set  of  cleaning  tools,  each  securely 
held  in  its  proper  place,  and  fitted  with  lock  and  key,  clamps, 
and  conveniently  arranged  handles. 

57.  Each  case  shall  contain  the  following: 

One  carpet  renovator  ^  in.  by  15  in. 

One  bare  floor  renovator,  15  in.  long,  with  curved  felt-cov- 
ered face. 

One  wall  brush,  with  skirted  bristles,  12  in.  long  and  y2  in. 
wide. 

One  hand  brush,  with  hose  connection  at  end,  8  in.  long 
and  2  in.  wide. 

One  4-in.  round  brush  for  relief  work. 

One  upholstery  renovator. 

One  corner  cleaner. 

One  radiator  tool. 

One  curved  stem  about  5  ft.  long. 

One  straight  extension  stem  5  ft.  long. 

At  least  one  hat  brush  with  the  system. 

58  to  68.  Same  as  for  Class  1. 

69.  Hose  Racks.  Furnish  and  properly  secure  in  place,  where 


218  VACUUM  CLEANING  SYSTEMS     • 

directed,  ....  hose  racks  in  basement,  ....  each  in  first  and 
second  stories  (.  . .  .  racks  in  all).  The  racks  to  be  constructed 
of  cast-iron,  galvanized  or  enamel  finish,  and  each  rack  to  be 
suitable  for  holding  75  ft.  of  hose  of  required  size. 

69a.  Hose.  There  must  be  furnished  with  each  hose  rack  75 
ft.  of  non-collapsible  hose  in  three  25-ft.  lengths. 

70.  Hose  to  be  \y2  in.  or  1^4  in-  inside  diameter,  best  quality 
rubber  hose,  reinforced  in  best  manner  to  absolutely  prevent 
collapse  at  highest  vacuum  obtainable  with  the  exhauster  fur- 
nished and  to  prevent  collapse  if  stepped  on.  Weight  of  hose 
to  be  not  over  12  oz.  per  linear  foot. 

71  to  73.  Same  as  for  Class  1. 

74.  On  completion  of  the  plant  the  pump  will  be  operated 
with  all  outlets  closed  and,  under  this  condition,  the  power  con- 
sumption must  not  be  more  than  50%  of  that  required  under 
test  conditions. 

75.  Same  as  for  Class  1. 

76.  To  test  the  capacity  of  the  plant,    ....   hose  lines  each 
75  ft.  long  shall  be  attached  to  the  inlets,  each  hose  to  be  fitted 
with   standard   vacometer   with    %-in.    opening.      Under   these 
conditions  a  vacuum  of  1  in.  mercury  must  be  maintained  in 
each  vacometer. 

77  and  78.  Same  as  for  Class  1. 

CLASS  5 

To  GIVE  WIDEST  COMPETITION. 

1.  Same  as  for  Class  1. 

2.  Exhauster  to  be  piston,  rotary  or  centrifugal  fan  type. 

3.  The  piston  type  of  exhauster  shall  be  double-acting  and 
so  designed  that  the  cylinder  clearance  shall  be  reduced  to  a 
minimum,   or  suitable   devices  shall  be   employed  to  minimize 
the  effect  of  large  clearances. 

4.  The  induction  and  eduction  valves  may  be  either  poppet, 
rotary  or  semi-rotary,   and   shall   operate  smoothly  and  noise- 
lessly. 

5.  The  piston  packing  shall  be  of  such  character  as  to  be 
practically  air  tight  under  working  conditions  and  constructed 
so  that  it  will  be  set  out  with  its  own  elasticity  without  the  use 


SPECIFICATIONS  219 

of  springs  of  any  sort.  If  metallic  rings  are  used,  they  must 
fill  the  grooves  in  which  they  are  fitted,  both  in  width  and  depth, 
and  must  be  concentric ;  that  is,  of  the  same  thickness  through- 
out. The  joint  in  the  ring  or  rings  to  be  lapped  in  width  but 
not  in  thickness,  and  if  more  than  one  ring  is  used  they  are 
to  be  placed  and  doweled  in  such  position  in  their  respective 
grooves  so  that  the  joints  will  be  at  least  one-fourth  of  the  cir- 
cumference apart. 

6.  The  piston  shall  have  no  chamber  or  space  into  which  air 
may  leak  from  either  side  of  the  piston.    All  openings  into  the 
body    of   the   piston   must   be    tightly   plugged   with   cast-iron 
plugs. 

7.  The  piston-rod  stuffing  box  to  be  of  such  size  and  depth 
that  if  soft  packing  is  used  it  can  be  kept  tight  without  undue 
pressure  from  the  gland.     If  metallic  packing  is  used,  it  must 
be  vacuum  tight  without  undue  pressure  on  the  rod.     Proper 
means-  shall  be  provided  for  the  continuous  lubrication  of  the 
piston  rod. 

8.  The  exhauster  of  the  piston  type  shall  be  fitted  with  an 
approved  cross-head  suitably  attached  to  the  piston  rod;  ma- 
chines having  an  extended  piston  rod  for  guide  purposes  will 
not  be  acceptable. 

Insert  paragraphs  3  to  15  from  specifications  for  Class  1. 

15a.  Reciprocating  exhauster  shall  be  provided  with  the  nec- 
essary devices  for  the  removal  of  the  heat  generated  by  friction 
and  compression,  that  shall  prevent  the  temperature  of  cylin- 
ders or  eduction  chambers  rising  more  than  100°  F.  above  the 
surrounding  atmosphere  after  two  hours'  continuous  operation 
under  full  load  conditions. 

15b.  Speed.  Reciprocating  exhauster  with  poppet  valves  shall 
operate  at  an  average  piston  speed  not  exceeding  200  ft.  per 
minute,  with  rotary  valves  not  exceeding  300  ft.  per  minute. 

Insert  paragraphs  16  and  17  from  specifications  for  Class  1. 

Omit  18. 

18a.  Base  Plate,  Foundation,  etc.  Provide  suitable  base  plate 
to  rigidly  support  the  exhauster  and  its  motor  as  a  unit,  which 
shall  be  large  enough  to  catch  all  drip  of  water  or  oil.  Provide 
a  raised  margin  and  pads  for  feet  of  exhauster  frame,  motor, 


220  VACUUM  CLEANING  SYSTEMS 

and  anchor  bolts,  high,  enough  to  prevent  any  drip  from  getting 
into  the  foundation  or  on  the  floor. 

18b.  Provide  suitable  foundation  of  brick  or  concrete,  to 
which  the  base  plate  shall  be  firmly  anchored.  The  founda- 
tion shall  be  built  on  top  of  the  cement  floor  of  the  basement, 
which  shall  be  picked  to  afford  proper  bond  for  the  foundation. 

18c.  Construct  the  foundation  of  such  «a  height  as  to  bring 
the  working  parts  of  the  machine  at  the  most  convenient  level 
for  operating  purposes.  Exposed  parts  of  the  foundation  to  be 
faced  with  best  grade  white  enameled  brick.  If  the  base  plate 
does  not  cover  the  foundation,  the  exposed  top  surface  is  to  be 
finished  with  enameled  brick  using  bull-nose  brick  on  all  edges 
and  corners. 

19  to  23.  Same  as  for  Class  1. 

23a.  The  guaranteed  efficiency  of  motor  shall  not  be  less  than 
78 %  at  half  load  and  not  less  than  84%  at  full  load. 

24  to  32.  Same  as  for  Class  1. 

32a.  Motors  shall  be  subject  to  shop  test  to  determine  effi- 
ciency, heating,  insulation,  etc.  Manufacturers'  certified  test 
sheets  of  motor,  giving  all  readings  taken  during  shop  test, 
together  with  calculated  results,  must  be  submitted  to  the  archi- 
tect for  approval  before  motor  is  shipped  from  factory. 

33.  Rheostat.  Furnish  and  install  where  shown,  upon  a 
slate  panel  hereinafter .  specified,  a  starting  rheostat  of  proper 
size  and  approved  make,  designed  for  the  particular  duty  it  has 
to  perform.  It  must  have  an  automatic  no- voltage  and  overload 
release.  All  resistance  for  rheostats  is  to  be  placed  on  the  back 
of  the  tablet.  Contacts  must  project  through  board  to  front 
side.  All  moving  parts  must  be  on  front  of  board. 

33a.  Tablet.  Furnish  and  place  where  shown,  a  slate  tablet 
not  less  than  1/4.  in  .thick,  supported  by  a  substantial  angle  bar 
frame,  so  placed  that  there  will  be  a  space  of  not  less  than  4  in. 
between  the  wall  and  back  of  resistance.  Mount  on  the  tablet 
one  double-pole,  250-volt  knife  switch,  with  two  250-volt  en- 
closed fuses  and  one  starting  rheostat,  as  specified  herein- 
before. The  connections  shall  be  on  the  back  of  the  tablet. 
The  space  between  the  column  and  the  tablet  shall  be  enclosed 


SPECIFICATIONS  221 

with  a  removable  diamond-mesh  grill  of  No.  10  iron  wire  in 
channel  frame. 

34,  35  and  36.  Same  as  for  Class  1. 

36a.  Automatic  Control.  Suitable  means  shall  be  provided 
in  connection  with  the  reciprocating  and  rotary  exhausters  that 
will  maintain  the  vacuum  in  the  separators  within  the  limit  of 
the  machine  at  point  found  to  be  most  desirable,  irrespective  of 
the  number  of  sweepers  in  operation. 

36b.  Controller  shall  consist  of  a  suitable  means  provided  in 
the  exhauster,  or  as  an  attachment  thereto,  which  will  auto- 
matically throw  the  exhauster  out  of  action  by  admitting  atmo- 
spheric pressure  to  the  exhauster  only,  but  not  to  the  system ;  or 
that  shall  cause  suction  from  the  system  to  cease  whenever  the 
vacuum  in  the  separators  rises  above  the  point  considered  de- 
sirable, and  throw  the  exhauster  into  action  when  the  vacuum 
falls  below  the  established  lower  limit. 

36c.  Vacuum  Breaker.  In  addition  to  the  controlling  devices 
above  specified,  if  a  reciprocating  or  rotary  exhauster  is  used, 
there  shall  be  placed  in  the  suction  pipe  to  the  exhauster  an 
approved  positive-acting  vacuum  breaker  having  opening  equiva- 
lent to  the  area  of  1-in.  diameter  pipe  and  set  to  open  at  12  in. 

36d.  If  centrifugal  fan  is  used,  no  control  or  vacuum  breaker 
will  be  required. 

37.  Dust  Separators.  There  musft  be  provided  at  least  one 
separator  between  the  pipe  lines  and  exhauster  having  a  volume 
of  not  less  than  3  cu.  ft.  per  sweeper  of  plant  capacity.  This 
separator  must  be  so  constructed  that  no  part  thereof  will  re- 
ceive the  direct  impact  of  the  dust.  If  rotary  exhauster  is  used, 
this  separator  must  also  contain  a  bag  so  placed  that  only  the 
lightest  dust  will  reach  same  and  must  be  arranged  to  be 
readily  cleaned  without  dismantling  the  separator.  If  a 
centrifugal  exhauster  is  used,  this  apparatus  may  or  may  not 
contain  a  bag,  and,  if  piston  pump  is  used,  this  separator  must 
contain  no  bags  or  screens  whatever.  If  a  piston  type  of  ex- 
hauster is  installed,  an  additional  separator  must  be  placed  be- 
tween the  first  separator  and  the  exhauster.  This  must  be  a 
wet  separator  and  may  be  contained  in  the  base  of  the  ma- 
chine or  consist  of  a  separate  tank. 


222  VACUUM  CLEANING  SYSTEMS 

Omit  38. 

38a.  Same  as  for  Class  1. 

38b.  Wet  separators,  whether  separate  from  or  integral  with 
the  base  of  the  machine,  must  be  provided  with  an  attachment 
which  will  positively  mix  the  air  and  water,  thoroughly  break 
up  all  bubbles,  separate  the  water  from  the  air,  and  prevent 
any  water  entering  the  exhauster  cylinder. 

38c.  Suitable  means  must  be  provided  to  automatically  equal- 
ize the  vacuum  between  wet  and  dry  separators  upon  the  shut- 
ting down  of  the  exhauster. 

38d.  The  separators  must  be  provided  with  suitable  openings 
for  access  to  the  interior  for  inspection  and  cleaning,  and  the 
interior  arrangement  of  the  separators  must  be  such  that  they 
may  be  readily  cleaned  without  dismantling. 

38e.  All  parts  of  the  wet  separator  tank  (if  used)  not  con- 
structed of  non-corrosive  metal  must  be  thoroughly  tinned  or 
galvanized  both  inside  and  outside.  The  interior  of  the  wet 
separator  formed  in  base  of  exhauster  shall  be  painted  with  at 
least  two  coats  of  asphalt  varnish  or  other  paint  suitable  to  pre- 
vent the  corrosion  of  same. 

38f.  Separators  must  be  provided  with  all  necessary  valves 
or  other  attachments  for  successful  operation,  including  a  sight 
glass  for  the  wet  separator  (if  used),  through  which  the  interior 
of  same  may  be  observed. 

38g.  The  wet  separator  (if  used)  shall  be  properly  connected 
to  water  supply  where  directed  and  discharge  to  sewer  where 
shown  on  plans. 

38h.  A  running  trap  with  clean-out  shall  be  installed  in  the 
waste  line. 

39  to  41.  Same  as  for  Class  1. 

41a.  Waste  and  water  pipe,  in  connection  with  wet  separator 
and  jacket,  except  waste  pipe  below  basement  floor,  to  be  stand- 
ard galvanized  wrought-iron  or  steel  screw-jointed  pipe  free 
from  burs.  Waste  pipe  below  the  basement  floor  is  to  be  best 
grade,  "extra  heavy"  cast-iron  pipe,  with  lead-calked  joints. 

42  to  45.  Same  as  for  Class  1. 


SPECIFICATIONS  223 

45a  Fittings  on  water  lines  to  be  standard  galvanized  beaded 
fittings. 

45b.  Fittings  on  waste  line  above  basement  floor  to  be  gal- 
vanized recessed  screw-jointed  drainage  fittings  and  those  below 
basement  floor  to  be  "extra  heavy"  cast-iron  with  hub  joints. 

46  to  50.  Same  as  for  Class  1. 

50a.  If  reciprocating  exhauster  is  used,  the  exhaust  pipe  is 
to  be  fitted  with  an  approved  first-class  muffler  not  less  than  12 
in.  in  diameter  and  60  in.  high,  closely  riveted  and  constructed 
of  galvanized  iron  not  less  than  %  in.  thick,  and  in  event  an 
exhauster  requiring  lubrication  is  furnished  this  muffler  is  to 
be  arranged  so  that  it  will  also  be  an  efficient  oil  separator.  Drip 
connection  is  to  be  arranged  at  bottom  of  muffler. 

51  to  56.  Same  as  for  Class  1. 

56a.  Tool  Cases.  Furnish  ....  approved  hardwood  cabinet 
finished  cases  for  cleaning  tools.  Each  case  to  be  made  as 
light  as  possible  and  of  convenient  fqrm  for  carrying  by  hand 
and  provided  with  a  complete  set  of  cleaning  tools,  each  se- 
curely held  in  its  proper  place,  and  fitted  with  lock  and  key, 
clamps,  and  conveniently  arranged  handles. 

57.  Each  case  will  contain  the  following: 

One  carpet  renovator,  with  slot  Y^  in.  by  not  less  than  12 
or  more  than  15  in.  long. 

One  bare  floor  renovator,  15  in.  long,  with  curved  felt-cov- 
ered face. 

One  wall  brush,  with  skirted  bristles,  12  in.  long  and  ^2  in. 
wide. 

One  hand  brush,  with  hose  connection  at  end,  8  in.  long  and 
2  in.  wide. 

One  4-in.  round  brush  for  relief  work. 

One  upholstery  renovator. 

One  corner  cleaner. 

One  radiator  tool. 

One  curved  stem  about  5  ft.  long. 

One  straight  extension  stem  5  ft.  long. 

At  least  one  hat  brush  with  the  system. 

58  to  64.  Same  as  for  Class  1. 

64a.  All  brushes  to  be  of  substantial  construction,  with  best 


224  VACUUM  CLEANING  SYSTEMS 

quality  bristles  set  in  close  rows  and  as  thick  as  possible,  skirted 
with  rubber,  leather,  or  chamois  skin,  so  that  all  air  entering 
renovator  will  pass  over  surface  being  cleaned. 
65  to  68.  Same  as  for  Class  1. 

69.  Hose  Racks.  Furnish  and  properly  secure  in  place,  where 
directed,    ....   hose  racks  in  basement,   ....   each  in  first  and 
second  stories  ( .  . . .  racks  in  all).     The  racks  to  be  constructed 
of  cast-iron,  galvanized  or  enamel  finish,  and  each  rack  to  be 
suitable  for  holding  75  ft.  of  hose  of  required  size. 

69a.  Hose.  There   must  be   furnished  with   each   hose   rack, 
75  ft.  of  non-collapsible  hose  in  three  25-ft.  lengths. 

70.  Hose  shall  not  be  less  than  1  in.  or  more  than  1%  in-  in- 
side diameter,  best  quality  rubber  hose,  reinforced  in  best  man- 
ner to  absolutely  prevent  collapse  at  highest  vacuum  obtainable 
with  the  exhauster  furnished  and  to  prevent  collapse  if  stepped 
on.    Weight  of  hose  to  be  not  over  12  oz.  per  linear  foot. 

71  to  73.  Same  as  for  -Class  1. 

74.  On  completion  of  the  plant,  the  pump  will  be  operated 
with  all  outlets  closed  and  under  this  condition  the  power  con- 
sumption must  not  be  more  than  50%  of  that  required  under 
test  conditions. 

75.  To  test  the  capacity  of  plant,  one  hose  line  100  ft.  long 
shall   be  attached   to   inlet  farthest  from  the  separator,   with 
standard  vacometer  with  ^2 -in.  opening  in  end  of  hose.     Hose 
lines  shall  be  attached  to  other  outlets,  each  with  50-ft.  hose 
and  vacometer  in  end  of  hose,    ....    vacometers  having   l/2-\n. 
opening  and    ....    vacometers  having   J^-in.   opening.     Under 
these  conditions  4  in.  mercury  must  be  maintained  in  vacometer 
at  end  of  100  ft.  of  hose. 

75a.  Test    of    Separators.  At    each    of points,    near — 

outlets  on  different  risers  selected  by  the representative, 

the  contractor  shall  furnish  and  spread  on  the  floor,  evenly  cov- 
ering an  area  of  approximately  50  sq.  ft.  for  each  outlet,  a  mix- 
ture of  6  Ibs.  of  dry  sharp  sand  that  will  pass  a  50-mesh  screen, 
3  Ibs.  of  fine  wheat  flour,  and  1  Ib.  of  finely  pulverized  charcoal, 
if  wet  separator  be  used,  and  6  Ibs.  of  Portland  cement,  if  bag 
be  used. 

75b.  Fifty  feet  of  hose  of  size  required  by  the  system  used 


SPECIFICATIONS  225 

shall  be  attached  to  each  of  the outlets,  and  the  surface  or 

surfaces  prepared  for  cleaning  shall  be  cleaned  simultaneously 
by  operators  provided  by  the  contractor  until  all  of  the  sand, 
flour  and  charcoal  has  been  taken  up,  when  the  exhauster  shall 
be  stopped  tand  the  dirt  removed  from  the  dry  separator  and 
spread  on  the  floor  again,  and  the  operation  of  cleaning  repeated 
until  the  mixture  has  been  handled  by  the  apparatus  four 
times.  If,  after  thoroughly  flushing  the  system  at  completion 
of  the  above  run,  any  dust  or  mud  is  found  in  the  cylinder, 
ports,  or  valve  chambers  of  the  displacement  exhauster,  or  if 
less  than  95%  of  the  dirt  removed  is  found  in  the  dry  separator 
of  the  centrifugal  exhauster,  it  shall  be  deemed  sufficient  ground 
for  the  rejection  of  the  separators.  If  bag  is  used,  same  must 
not  be  disturbed  until  after  capacity  test,  which  will  be  made 
with  material  in  separator  after  being  picked  up  the  fourth 
time. 

76-77.  Same  as  for  Class  1.  • 

78.  Evaluation  of  proposal  (for  4-sweeper  plant)  :  No  pro- 
posal will  be  considered  which  contemplates  furnishing  an  ex- 
hauster requiring  more  power  to  operate  under  test  conditions 
than : 

Full  load,  14  K.  W. ;  three-quarter  load,  12.25  K.  W. ;  one- 
half  load,  10.5  K.  W. 

Test  Requirement:  Paragraph  75  to  be  considered  full  load. 
To  reduce  the  load  to  three-quarters,  one  %-in.  vacometer  open- 
ing to  be  closed ;  to  produce  one-half  load,  one  ^-in.  opening 
to  be  closed  in  addition  to  the  J^-in.  opening. 

Bidders  are  requested  to  state  in  proposal  the  power  con- 
sumption required  by  their  apparatus  at  full,  three-quarters 
and  one-half  loads,  and  in  case  the  guarantees  of  the  various 
bidders  differ,  they  will  be  evaluated  'as  follows  for  the  purpose 
of  comparison: 

For  each  full  K.  W.  of  power  consumption  or  fractional  part 
thereof  there  will  be  allowed  the  following  amount  or  propor- 
tionate parts  for  fractional  parts  of  a  K.  W.  hour  at  the  various 
loads : 

Per  Cent,  of  Full  Load.         100  '  75  50 

Amount     $156.00        $62.00        $94.00 


226  VACUUM  CLEANING  SYSTEMS 

As  an  illustration,  let  it  be  assumed  that  proposals  have  been 
received  offering  equipment  in  accordance  with  specification 
requirements,  and  the  one  offering  the  most  economical  appa- 
ratus based  on  guaranteed  power  consumption  names  the  highest 
price  for  the  installation. 

To  determine  if  the  purchaser  will  be  justified  in  accepting 
the  highest  proposal,  let  it  be  assumed  that  he  has  guaranteed 
a  power  consumption  of  1  K.  W.  less  at  full  load,  0.75  K.  W. 
less  at  three-quarters  load,  and  0.25  K.  W.  more  at  half-load 
than  the  lowest  bidder.  Under  these  conditions  the  algebraic 
sum  of  the  saving  of  the  higher  bidder  over  the  lower  bidder 
would  be  156+46.50— 23.50=179,  which  is  the  additional 
amount  in  dollars  which  the  purchaser  would  be  warranted  in 
paying  for  the  apparatus  of  higher  efficiency. 

In  making  the  economy  test  to  determine  if  the  guaranteed 
power  consumption  has  been  fulfilled,  an  integrating  watt 
meter,  previously  calibrated  and  found  correct,  will  be  placed 
in  circuit  and  a  two-hour  run  made  at  each  load  and  the  power 
consumption  based  on  the  meter  readings. 

Penalty. — It  must  be  distinctly  understood  to  be  one  of  the 
conditions  under  which  bids  are  to  be  submitted  for  the  work 
embraced  in  this  specification  that  the  apparatus  shall  meet 
every  requirement  of  the  specification  and  the  guaranty  for 
efficiency  under  which  conditions  the  contract  price  will  be  paid. 
In  the  event  the  apparatus  tested  fails  to  meet  the  specified  re- 
quirements for  capacity  or  economy,  or  both,  the  Architect  shall 
have  the  right  to  reject  the  apparatus,  absolutely,  and  require 
the  installation  of  satisfactory  apparatus,  which  shall  comply 
with  the  contract  requirements;  or  if  he  elects  to  accept  the 
same,  in  the  event  the  capacity  or  efficiency  at  any  load  (irre- 
spective of  other  loads)  is  less  than  that  named  in  the  proposal, 
then  the  contract  price  shall  be  the  amount  named  in  the  con- 
tract for  a  satisfactory  plant,  less  the  amount  of  deficiencies 
shown  by  the  test  based  on  the  following: 

For  Capacity. — $500.00  for  each  inch  of  vacuum  and  a  pro- 
portionate part  thereof  for  each  fraction  of  an  inch  below  the 
4  in.  required  in  vacometer  when  operating  under  full  load. 

For  Economy. — Deduction  for  each  K.  W.  or  a  proportion- 


SPECIFICATIONS  227 

ate  part  thereof  for  each  fraction  thereof  required  in  excess  of 

guarantee. 

Percentage  of  Full  Load          100  75  50 

Penalty     $229.00        $93.00      $141.00 


This  evaluation  was  based  on  the  same  time  of  operation  and 
cost  of  current  as  that  used  in  illustration  under  tests  (Chapter 
XII). 

The  maximum  power  to  be  allowed  for  plants  of  various 
capacities  should  be  as  follows : 

Capacity  in  100%  75%  50% 

Sweepers  of  Load      of  Load      of  Load 

8  24  20  17 

6  20  18  15 

4  14  12.25  10.5 

2  7.5  6.25 

In  event  that  the  plant  is  to  be  run  with  vacuum  "on  tap," 
as  in  a  hotel,  a  guaranteed  power  consumption  at  no  load  should 
be  required  and  evaluated  on  the  number  of  hours  the  plant 
will  probably  operate  under  these  conditions.  This  will  be  the 
largest  item  in  the  evaluation  under  such  conditions. 


CHAPTER  XV. 
PORTABLE  VACUUM  CLEANERS. 

While  this  book  is  primarily  intended  to  deal  only  with 
vacuum  cleaning  systems,  which  would  limit  the  work  to  such 
apparatus  as  is  permanently  installed  within  the  building  to  be 
cleaned,  the  author  considers  that  it  would  not  be  complete 
without  some  mention  of  the  portable  cleaners  which  are  so 
popular  at  the  present  time. 

On  first  consideration,  the  portable  cleaner  would  appear  to 
have  a  considerable  advantage  over  the  stationary  type  in  that 
the  length  of  hose  is  usually  limited  to  not  over  15  ft.  and 
there  is  no  pipe  line,  which  results  in  the  elimination  of 
practically  all  friction  loss,  giving  practically  the  same  vacuum 
at  the  renovator  as  at  the  exhauster.  This  should  result  in  a 
saving  of  practically  50%  of  the  power  required  to  operate  the 
exhauster. 

Referring  to  Chapter  XII,  we  find  that  the  power  required 
to  operate  a  really  efficient  vacuum  cleaning  system  is  approxi- 
mately 2.5  H.  P.  per  sweeper.  If  a  portable  cleaner,  with  the 
same  efficiency  and  capacity,  be  built,  it  would  require  at  least 

iy2  H.  P. 

Such  a  cleaner  would  not  be  portable  in  the .  sense  of  the 
term  as  applied  to  the  most  popular  cleaners  today.  The  sam^ 
type  has  been  built  on  special  order  by  the  American  Radi- 
ator Company,  which  mounted  its  ~Ll/2  H.  P.  Arco  Wand  machine 
on  a  truck.  This  cleaner  weighs  several  hundred  pounds  and 
could  be  moved  up  and  down  stairs  about  as  easily  as  a  sewing 
machine  and  would  not  be  of  any  service  in  a  building  not 
equipped  with  elevators.  The  power  required  to  operate  this 
cleaner  is  also  so  great  that  special  power  wiring  and  large 
capacity  outlet  plugs  have  to  be  installed  throughout  the  build- 
ing. Such  equipment  has  been  provided  in  at  least  two  depart- 
ment stores  where  these  cleaners  are  in  use.  This  means  that 

228 


PORTABLE  VACUUM  CLEANERS       229 

one  wires  his  building  for  vacuum  cleaning  instead  of  piping 
it,  and  there  is  also  the  necessity  of  moving  a  heavy  machine 
about  to  do  the  same  work  as  a  stationary  plant. 

It  would  appear  to  the  author  that  the  cost  of  wiring  would 
about  equal  that  of  piping  and  that  the  additional  labor  re- 
quired to  move  the  machine  about  would  cost  as  much  as  the 
additional  power  needed  by  the  stationary  exhauster. 

This  cleaner,  as  well  as  all  other  portable  cleaners,  discharges 
the  air  from  the  exhauster  directly  back  into  the  apartment 
cleaned,  and  is  open  to  the  same  objection  that  was  raised 
against  the  early  compressed  air  cleaners.  While  all  the  dust 
may  be  caught  by  the  dust  bag,  the  microbes  are  allowed  to 
escape  with  the  air  and  the  cleaner  is  not  a  sanitary  device 
by  any  manner  of  means. 

There  are  a  few  portable  machines  using  rotary  exhausters 
of  the  Root  type,  and  piston  pumps,  all  of  which  'are  heavy  to 
move  about  and,  in  making  them  as  light  as  possible,  the 
efficiency  of  the  exhauster  has  been  sacrificed.  These  machines 
will  do  the  same  quality  of  cleaning  as  the  stationary  plants 
recommended  for  residence  work  and  they  require  about  £4 
H.  P.,  which  is  no  less  than  is  needed  for  a  stationary  plant 
of  the  same  capacity  and  efficiency. 

The  most  popular  type  of  portable  cleaner  is  one  which  can 
be  attached  to  a  socket  or  plug  connected  with  the  lighting 
system.  This  should  limit  the  power  consumption  to  %  H.  P. 
However,  many  of  these  cleaners  use  as  much  as  400  watts 
and  a  fair  average  for  cleaners  retailing  at  about  $125.00  is 
250  watts.  Such  cleaners  will  exhaust  about  25  cu.  ft.  of  air 
with  a  vacuum  of  1  in.  mercury  at  the  vacometer,  a  ^-in. 
orifice  being  used.  The  theoretical  power  required  to  move  the 
air  is  approximately  50  watts  and  the  overall  efficiency  of  these 
cleaners  is,  therefore,  about  20%,  as  against  40%  to  50%  in 
a  good,  one-sweeper  stationary  plant.  The  power  expended  in 
operating  these  portable  cleaners  in  proportion  to  the  work 
done  is  no  less  than  with  an  efficient  stationary  plant. 

Portable  cleaners  have  been  made  in  many  types  but  prac- 
tically all  the  standard  makes  use  one  or  two  forms  of  vacuum 
producers,  either  the  diaphragm  pump  or  the  single  or  multi- 


230  VACUUM  CLEANING  SYSTEMS 

stage  fan.  The  pumps  of  the  former  type  are  able  to  produce 
a  vacuum  as  high  as  6  in.  to  10  in.  of  mercury,  when  no  air  is 
passing,  and  will  displace  as  high  as  30  cu.  ft.  of  free  air  per 
minute,  when  operated  with  a  free  inlet.  They  produce  about 
1  in.  of  mercury  at  the  carpet  renovator  when  operated  on  an 
ordinary  carpet.  When  small-sized  upholstery  renovators  are 
used,  a  much  higher  vacuum  is  possible.  When  operated  with 
bare  floor  renovators  or  brushes,  the  quantity  of  air  exhausted 
is  not  much  over  20  cu.  ft.  per  minute  and  they  make  very  in- 
efficient bare  floor  and  wall  cleaners,  but  will  do  thorough  carpet 
and  upholstery  cleaning  provided  a  small  enough  renovator  is 
used. 

Machines  using  a  multi-stage  fan  will  produce  a  maximum 
vacuum  of  approximately  2  in.  of  mercury  when  exhausting  no 
air,  and  will  produce  a  vacuum  of  approximately  1  in.  of  mer- 
cury when  operated  on  an  ordinary  carpet.  With  an  unrestricted 
inlet,  they  will  exhaust  from  40  to  50  cu.  ft.  of  air  per  minute. 
When  operated  on  a  bare  floor,  they  will  exhaust  approxi- 
mately 30  cu.  ft.  of  free  air  per  minute.  They  are,  therefore, 
more  efficient  floor  cleaners  than  the  pumps,  but  cannot  do 
thorough  carpet  and  upholstery  cleaning,  no  matter  how  small 
the  renovator. 

The  smaller-fan  type  of  machines,  in  which  the  fan  is  placed 
integral  with  the  carpet  renovator  and  in  which  hose  is  not 
used  in  cleaning  floors  or  carpets,  are  provided  with  a  single- 
stage  fan.  They  produce  a  suction  of  not  exceeding  y2  in.  of 
mercury  when  no  air  is  exhausted  and  will  exhaust  from  5  to 
10  cu.  ft.  of  free  air  per  minute  when  operated  on  a  carpet. 
With  a  free  inlet  they  will  exhaust  from  15  to  20  cu.  ft.  of 
free  air  per  minute.  These  machines  are  little  if  any  better 
than  ordinary  carpet  sweepers. 

Machines  of  this  type  are  open  to  another  objection  in  that 
the  dust  bag  is  placed  on  the  outlet  of  the  fan  and  the  dust  in 
the  bag  is  continually  agitated  by  the  passage  of  the  air,  with 
the  result  that  all  the  finer  particles  of  the  dust  are  blown 
through  the  bag  back  into  the  apartment.  To  be  effective,  the 
dust  bag  must  always  be  placed  on  the  suction  side  of  the  ex- 
hauster and  should  be  so  arranged  that  the  dust  will  not  quickly 


PORTABLE  VACUUM  CLEANERS      231 

cover  the  entire  area  of  the  bag,  for,  when  this  occurs,  the  suc- 
tion is  quickly  reduced  to  such  an  extent  that  no  further  clean- 
ing can  be  done  until  the  bag  has  been  cleaned. 

There  is  another  type  of  mechanical  cleaner  manufactured 
by  the  Hoover  Suction  Sweeper  Company  which  is  provided 
with  a  mechanically-operated  brush  for  loosening  the  dirt  from 
the  carpet.  The  dust  is  then  conveyed  through  a  single-stage 
fan  to  a  dust  bag.  The  cleaner  does  not  depend  on  the  vacuum 
to  loosen  the  dirt  and  will  do  quite  effective  carpet  cleaning  with 
a  small  expenditure  of  power.  Owing  to  the  small  suction 
produced,  it  is  of  little  value  for  cleaning  anything  but  carpets. 

From  the  experience  the  author  has  had  with  portable  vacuum 
cleaners,  some  thirty  makes  having  been  tested  for  the  Treasury 
Department  by  him  and  by  the  Bureau  of  Standards,  the  use 
of  such  cleaners  is  not  considered  'as  either  an  efficient  or  sani- 
tary means  of  mechanical  cleaning. 

If  a  cleaner  requiring  small  power  is  required,  one  of  the 
smaller  stationary  plants,  costing  not  over  $300.00  and  operating 
with  y2  or  y^  H.  P.,  is  considered  a  better  investment  than 
$125.00  paid  for  a  portable  cleaner. 

If  the  purchaser  feels  that  he  cannot  afford  to  pay  more  than 
$125.00  for  his  vacuum  cleaner,  a  type  such  as  the  Water  Witch 
can  be  furnished  for  this  price.  This  cleaner  is  placed  in  the 
basement,  with  arrangements  for  starting  same  from  any  floor. 
The  manufacturers  state  that  this  apparatus  produces  a  vacuum 
of  2  in.  mercury  in  a  carpet  renovator,  4  in.  mercury  in  an 
upholstery  renovator  and  exhausts  25  to  30  cu.  ft.  of  free  air 
per  minute  with  open  hose.  The  machine  operates  by  water 
pressure  and  the  manufacturers  state  that  it  requires  about  6 
to  8  gals,  of  water  per  minute.  All  air  is  exhausted  outside  of 
the  building  and  all  dust  washed  down  the  sewer  with  the  ex- 
haust water.  It  is  therefore,  a  fairly  efficient  and  sanitary 
cleaning  system. 

The  statements  made  above  apply  to  parties  who  own  their 
residences  and  occupy  offices  in  modern  buildings.  There  are, 
besides  these,  a  great  many  who  live  in  rented  houses  and 
apartments  or  occupy  offices  in  buildings  where  the  owners  are 
not  sufficiently  progressive  to  install  stationary  cleaning  plants. 


232  VACUUM  CLEANING  SYSTEMS 

To  supply  the  needs  of  this  class  is  evidently  the  field  of  the 
portable  cleaner,  as  even  the  poorest  of  these  machines  is  more 
effective  in  the  removal  of  dust  and  dirt  than  the  broom  and 
carpet  sweeper. 

The  selection  of  a  portable  cleaner  by  one  who  must  neces 
sarily  resort  to  the  use  of  such  a  cleaner  should  be  made  with 
care.  The  motor  should  be  looked  into  and  only  one  which  has 
brushes  readily  removable  and  one  in  which  the  condition  of 
the  brushes  can  be  easily  noted  should  be  selected.  Lubrication 
is  important.  A  good  cleaner  should  be  so  constructed  that  it 
can  be  operated  for  at  least  100  hours  without  relubrication. 

The  dust  bag  should  always  be  on  the  suction  side  of  the 
vacuum  producer  and  of  such  a  design  and  construction  that 
at  least  y2  peck  of  a  mixture  of  40%  sand,  30%  flour, 
15%  sweepings  and  15%  Portland  cement  can  be  picked  up 
from  the  floor  and  retained  in  the  bag  and  the  machine  still  be 
capable  of  picking  up  material  from  a  bare  floor. 

A  good  test  for  capacity  of  a  portable  machine  is  to  pick  up 
YZ  peck  of  such  material,  then  fit  a  thin  disk  with  Ji-in. 
diameter  opening  over  the  end  of  the  hose.  A  machine,  to  be 
of  any  value,  should  show  a  suction  of  3  in.  water  and  a  first- 
class  machine  will  show  8  in.  under  these  conditions.  This  will 
do  fairly  good  bare  floor  work.  To  ascertain  if  the  machine 
will  clean  carpets,  use  a  similar  disk  with  ^-in.  diameter  open- 
ing, when  a  suction  of  7  in.  water  indicates  the  lowest  value 
and  16  in.  about  the  best  that  can  be  obtained  from  any  port- 
able cleaner.  Cleaners  must  be  readily  portable  and  should 
not  weigh  exceeding  75  Ibs. 


'vrvr 


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